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Question 1
Correct
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A 58-year-old male comes to the rheumatology clinic complaining of persistent pain caused by his rheumatoid arthritis. He is prescribed an NSAID for pain management. How does this medication impact his kidneys?
Your Answer: Afferent arteriole constriction
Explanation:NSAIDs are commonly used drugs that have anti-inflammatory properties. They work by inhibiting the enzymes COX-1 and COX-2, which are responsible for synthesizing prostanoids such as prostaglandins and thromboxanes.
Prostaglandins play a crucial role in the kidney by causing vasodilation of the afferent arterioles in the glomeruli. This increases blood flow into the glomerulus and leads to an increase in the glomerular filtration rate (GFR).
When NSAIDs inhibit the COX enzymes, they reduce the levels of prostaglandins in the body. This results in a loss of vasodilation in the afferent arterioles, which leads to reduced renal perfusion and a decrease in GFR.
The Impact of NSAIDs on Kidney Function
NSAIDs are commonly used anti-inflammatory drugs that work by inhibiting the enzymes COX-1 and COX-2, which are responsible for the synthesis of prostanoids such as prostaglandins and thromboxanes. In the kidneys, prostaglandins play a crucial role in vasodilating the afferent arterioles of the glomeruli, allowing for increased blood flow and a higher glomerular filtration rate (GFR).
However, when NSAIDs inhibit the COX enzymes, the levels of prostaglandins decrease, leading to a reduction in afferent arteriole vasodilation and subsequently, a decrease in renal perfusion and GFR. This can have negative consequences for kidney function, particularly in individuals with pre-existing kidney disease or those taking high doses of NSAIDs for prolonged periods of time.
It is important for healthcare providers to consider the potential impact of NSAIDs on kidney function and to monitor patients accordingly, especially those at higher risk for kidney damage. Alternative treatments or lower doses of NSAIDs may be recommended to minimize the risk of kidney injury.
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This question is part of the following fields:
- Renal System
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Question 2
Correct
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A 50-year-old male is brought back to a surgical ward after a renal transplant. Diuresis suddenly decreases 2 hours after the transplantation. The patient is quickly transferred back to surgery where the transplanted kidney displays signs of hyperacute rejection and is removed. Histopathological examination confirms hyperacute rejection.
What type of reaction has this patient undergone?Your Answer: Type II hypersensitivity
Explanation:Hyperacute transplant rejection is a type II hypersensitivity reaction, which is characterized by a cytotoxic response caused by pre-existing antibodies to the ABO or HLA antigens. This reaction leads to widespread thrombosis and ischaemia/necrosis within the transplanted organ, necessitating its surgical removal.
In contrast, type I hypersensitivity is an immediate IgE-mediated reaction that occurs within minutes, while type III hypersensitivity is an IgM-mediated reaction that involves the formation of circulating immune complexes. Type IV hypersensitivity is a cell-mediated response that takes weeks to develop and is seen in chronic graft rejections. Finally, type V hypersensitivity is an autoimmune reaction that involves the binding of auto-antibodies to cell surface receptors, either preventing the intended ligand binding or mimicking its effects.
The HLA system, also known as the major histocompatibility complex (MHC), is located on chromosome 6 and is responsible for human leucocyte antigens. Class 1 antigens include A, B, and C, while class 2 antigens include DP, DQ, and DR. When matching for a renal transplant, the importance of HLA antigens is ranked as DR > B > A.
Graft survival rates for renal transplants are high, with a 90% survival rate at one year and a 60% survival rate at ten years for cadaveric transplants. Living-donor transplants have even higher survival rates, with a 95% survival rate at one year and a 70% survival rate at ten years. However, postoperative problems can occur, such as acute tubular necrosis of the graft, vascular thrombosis, urine leakage, and urinary tract infections.
Hyperacute rejection can occur within minutes to hours after a transplant and is caused by pre-existing antibodies against ABO or HLA antigens. This type of rejection is an example of a type II hypersensitivity reaction and leads to widespread thrombosis of graft vessels, resulting in ischemia and necrosis of the transplanted organ. Unfortunately, there is no treatment available for hyperacute rejection, and the graft must be removed.
Acute graft failure, which occurs within six months of a transplant, is usually due to mismatched HLA and is caused by cell-mediated cytotoxic T cells. This type of failure is usually asymptomatic and is detected by a rising creatinine, pyuria, and proteinuria. Other causes of acute graft failure include cytomegalovirus infection, but it may be reversible with steroids and immunosuppressants.
Chronic graft failure, which occurs after six months of a transplant, is caused by both antibody and cell-mediated mechanisms that lead to fibrosis of the transplanted kidney, known as chronic allograft nephropathy. The recurrence of the original renal disease, such as MCGN, IgA, or FSGS, can also cause chronic graft failure.
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This question is part of the following fields:
- Renal System
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Question 3
Correct
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A 55-year-old man presents to the emergency department after his GP performed an ECG due to complaints of palpitations, which showed active changes associated with hyperkalaemia. The emergency department confirms these changes and an arterial blood gas reveals a serum potassium level of 6.9 mmol/l. The patient is promptly initiated on treatment. What intervention will stabilize the cardiac membrane?
Your Answer: Calcium gluconate
Explanation:Hyperkalaemia is present in the patient.
Although all the options are used in treating hyperkalaemia, they have distinct roles. Calcium gluconate is the only option used to stabilise the cardiac membrane.
Hyperkalaemia is a condition where there is an excess of potassium in the blood. The levels of potassium in the plasma are regulated by various factors such as aldosterone, insulin levels, and acid-base balance. When there is metabolic acidosis, hyperkalaemia can occur as hydrogen and potassium ions compete with each other for exchange with sodium ions across cell membranes and in the distal tubule. The ECG changes that can be seen in hyperkalaemia include tall-tented T waves, small P waves, widened QRS leading to a sinusoidal pattern, and asystole.
There are several causes of hyperkalaemia, including acute kidney injury, drugs such as potassium sparing diuretics, ACE inhibitors, angiotensin 2 receptor blockers, spironolactone, ciclosporin, and heparin, metabolic acidosis, Addison’s disease, rhabdomyolysis, and massive blood transfusion. Foods that are high in potassium include salt substitutes, bananas, oranges, kiwi fruit, avocado, spinach, and tomatoes.
It is important to note that beta-blockers can interfere with potassium transport into cells and potentially cause hyperkalaemia in renal failure patients. In contrast, beta-agonists such as Salbutamol are sometimes used as emergency treatment. Additionally, both unfractionated and low-molecular weight heparin can cause hyperkalaemia by inhibiting aldosterone secretion.
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This question is part of the following fields:
- Renal System
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Question 4
Incorrect
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A 65-year-old man is undergoing assessment for polycythemia and has no history of smoking. What type of solid-organ cancer could be a possible cause?
Your Answer: Prostate cancer
Correct Answer: Renal cell carcinoma
Explanation:Renal cell carcinoma has the potential to secrete various hormones such as erythropoietin, PTHrP, renin, or ACTH. This can lead to secondary polycythemia, hypercalcemia, or other related conditions. On the other hand, small cell lung cancer can cause ectopic secretion of ACTH or ADH, but not erythropoietin. Pituitary tumors, on the other hand, may secrete prolactin.
Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.
Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.
The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.
In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.
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This question is part of the following fields:
- Renal System
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Question 5
Incorrect
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A 23-year-old male presents to the emergency department with decreased level of consciousness after a night of excessive alcohol intake. He is observed to have increased urine output. There is no history of substance abuse according to his companions.
What is the probable cause of the patient's polyuria?Your Answer: Cranial diabetes insipidus
Correct Answer: antidiuretic hormone inhibition
Explanation:Alcohol bingeing can result in the suppression of ADH in the posterior pituitary gland, leading to polyuria. This occurs because alcohol inhibits ADH, which reduces the insertion of aquaporins in the collecting tubules of the nephron. As a result, water reabsorption is reduced, leading to polyuria. The other options provided are incorrect because they do not accurately describe the mechanism by which alcohol causes polyuria. Central diabetes insipidus is a disorder of ADH production in the brain, while nephrogenic diabetes insipidus is caused by kidney pathology. Osmotic diuresis occurs when solutes such as glucose and urea increase the osmotic pressure in the renal tubules, leading to water retention, but this is not the primary mechanism by which alcohol causes polyuria.
Polyuria, or excessive urination, can be caused by a variety of factors. A recent review in the BMJ categorizes these causes by their frequency of occurrence. The most common causes of polyuria include the use of diuretics, caffeine, and alcohol, as well as diabetes mellitus, lithium, and heart failure. Less common causes include hypercalcaemia and hyperthyroidism, while rare causes include chronic renal failure, primary polydipsia, and hypokalaemia. The least common cause of polyuria is diabetes insipidus, which occurs in less than 1 in 10,000 cases. It is important to note that while these frequencies may not align with exam questions, understanding the potential causes of polyuria can aid in diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 6
Correct
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A 33-year-old individual presents to the emergency department in an intoxicated state after a night of drinking. Although there are no immediate medical concerns, the patient is visibly under the influence of alcohol, exhibiting unsteady gait, reduced social inhibition, and mild slurring of speech. Additionally, the patient is observed to be urinating frequently.
What is the probable mechanism behind the increased frequency of urination in this patient?Your Answer: Suppression of antidiuretic hormone (ADH) release from the posterior pituitary gland
Explanation:Polyuria, or excessive urination, can be caused by a variety of factors. A recent review in the BMJ categorizes these causes by their frequency of occurrence. The most common causes of polyuria include the use of diuretics, caffeine, and alcohol, as well as diabetes mellitus, lithium, and heart failure. Less common causes include hypercalcaemia and hyperthyroidism, while rare causes include chronic renal failure, primary polydipsia, and hypokalaemia. The least common cause of polyuria is diabetes insipidus, which occurs in less than 1 in 10,000 cases. It is important to note that while these frequencies may not align with exam questions, understanding the potential causes of polyuria can aid in diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 7
Correct
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A 38-year-old female visits her doctor complaining of tingling sensations around her mouth and frequent muscle cramps. During the blood pressure check, her wrist and fingers start to cramp and flex. Despite these symptoms, she appears to be in good health.
What condition is the most probable diagnosis?Your Answer: Hypocalcaemia
Explanation:Hypocalcaemia is characterized by perioral paraesthesia, cramps, tetany, and convulsions. The female in this scenario is displaying these symptoms, along with a positive Trousseau’s sign and potentially a positive Chvostek’s sign. Hypocalcaemia is commonly caused by hyperparathyroidism, vitamin D deficiency, or phosphate infusions.
Hyperkalaemia is when there is an elevated level of potassium in the blood, which can be caused by chronic kidney disease, dehydration, and certain medications such as spironolactone. Symptoms may include muscle weakness, heart palpitations, and nausea and vomiting.
Hypermagnesaemia is rare and can cause decreased respiratory rate, muscle weakness, and decreased reflexes. It may be caused by renal failure, excessive dietary intake, or increased cell destruction.
Hypokalaemia is relatively common and can cause weakness, fatigue, and muscle cramps. It may be caused by diuretic use, low dietary intake, or vomiting.
Hyponatraemia may also cause cramps, but typically presents with nausea and vomiting, fatigue, confusion, and in severe cases, seizures or coma. Causes may include syndrome of inappropriate ADH release (SIADH), excessive fluid intake, and certain medications such as diuretics, SSRIs, and antipsychotics.
Hypocalcaemia: Symptoms and Signs
Hypocalcaemia is a condition characterized by low levels of calcium in the blood. As calcium is essential for proper muscle and nerve function, many of the symptoms and signs of hypocalcaemia are related to neuromuscular excitability. The most common features of hypocalcaemia include muscle twitching, cramping, and spasms, as well as perioral paraesthesia. In chronic cases, patients may experience depression and cataracts. An electrocardiogram (ECG) may show a prolonged QT interval.
Two specific signs that are commonly used to diagnose hypocalcaemia are Trousseau’s sign and Chvostek’s sign. Trousseau’s sign is observed when the brachial artery is occluded by inflating the blood pressure cuff and maintaining pressure above systolic. This causes wrist flexion and fingers to be drawn together, which is seen in around 95% of patients with hypocalcaemia and around 1% of normocalcaemic people. Chvostek’s sign is observed when tapping over the parotid gland causes facial muscles to twitch. This sign is seen in around 70% of patients with hypocalcaemia and around 10% of normocalcaemic people. Overall, hypocalcaemia can cause a range of symptoms and signs that are related to neuromuscular excitability, and specific diagnostic signs can be used to confirm the diagnosis.
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This question is part of the following fields:
- Renal System
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Question 8
Correct
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A 44-year-old woman presents to the emergency department with abdominal pain. She reports feeling generally unwell for the last 2 days but says today is the worst she has felt.
On examination, her heart rate is 110 beats/min with a blood pressure of 106/70mmHg and a respiratory rate of 27 breaths/min.
An arterial blood gas is taken:
pH 7.11 (7.35 - 7.45)
pO2 11.2 kPa (10.5 - 13.5)
pCO2 4.9 kPa (4.7 - 6.0)
Sodium 142 mmol/L (135 - 145)
Potassium 5.1 mmol/L (3.5 - 5.5)
Chloride 111 mmol/L (96 - 106)
Bicarbonate 17 mmol/L (22 - 28)
Lactate 2.6 mmol/L (0.6 - 1.9)
Glucose 10.5 mmol/L (4 - 7)
What is the most likely cause for this patient's investigation findings?Your Answer: Diarrhoea
Explanation:The patient’s condition is caused by diarrhoea, which is a common cause of normal anion gap metabolic acidosis. The anion gap is calculated by subtracting the sum of chloride and bicarbonate levels from the sum of sodium and potassium levels. In this case, the anion gap is within the normal range of 10-18 mmol/L. Other causes of normal anion gap metabolic acidosis include ureterosigmoidostomy, renal tubular acidosis, Addison’s disease, and certain medications. Raised anion gap metabolic acidosis can be remembered using the mnemonic ‘MUDPILES’, which includes causes such as methanol poisoning, diabetic ketoacidosis, and salicylate poisoning. However, these are not relevant in this case as the patient has a normal anion gap metabolic acidosis caused by diarrhoea.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 9
Correct
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A 65-year-old man is being evaluated at the liver clinic of his local hospital. The physician in charge observes that he has developed ascites due to secondary hyperaldosteronism, which is common in patients with liver cirrhosis. To counteract the elevated aldosterone levels by blocking its action in the nephron, she intends to initiate a diuretic.
Which part of the nephron is the diuretic most likely to target in this patient?Your Answer: Cortical collecting ducts
Explanation:Spironolactone is a diuretic that acts as an aldosterone antagonist on the cortical collecting ducts. It is the first-line treatment for controlling ascites in this gentleman as it blocks the secondary hyperaldosteronism underlying the condition. The main site of action for spironolactone’s diuretic effects is the cortical collecting duct.
Spironolactone is a medication that works as an aldosterone antagonist in the cortical collecting duct. It is used to treat various conditions such as ascites, hypertension, heart failure, nephrotic syndrome, and Conn’s syndrome. In patients with cirrhosis, spironolactone is often prescribed in relatively large doses of 100 or 200 mg to counteract secondary hyperaldosteronism. It is also used as a NICE ‘step 4’ treatment for hypertension. In addition, spironolactone has been shown to reduce all-cause mortality in patients with NYHA III + IV heart failure who are already taking an ACE inhibitor, according to the RALES study.
However, spironolactone can cause adverse effects such as hyperkalaemia and gynaecomastia, although the latter is less common with eplerenone. It is important to monitor potassium levels in patients taking spironolactone to prevent hyperkalaemia, which can lead to serious complications such as cardiac arrhythmias. Overall, spironolactone is a useful medication for treating various conditions, but its potential adverse effects should be carefully considered and monitored.
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This question is part of the following fields:
- Renal System
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Question 10
Incorrect
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An 85-year-old woman presents with a painful left leg and is diagnosed with erysipelas. She is admitted and prescribed penicillin in accordance with trust guidelines. However, after two days of inpatient treatment, the patient becomes anuric and confused. A repeat set of U&Es reveals a significant increase in creatinine levels. What is the probable mechanism by which penicillin caused kidney injury in this elderly patient?
Your Answer: Renal artery vasoconstriction
Correct Answer: Acute interstitial nephritis
Explanation:AKI can be caused by penicillin due to its tendency to induce acute interstitial nephritis. This condition is characterized by inflammation in the renal interstitium and is known to occur with various medications, such as NSAIDs, antibiotics, and anticonvulsants. While the other choices may lead to acute kidney injury, they are not typically associated with penicillin antibiotics.
Acute interstitial nephritis is a condition that is responsible for a quarter of all drug-induced acute kidney injuries. The most common cause of this condition is drugs, particularly antibiotics such as penicillin and rifampicin, as well as NSAIDs, allopurinol, and furosemide. Systemic diseases like SLE, sarcoidosis, and Sjögren’s syndrome, as well as infections like Hanta virus and staphylococci, can also cause acute interstitial nephritis. The histology of this condition shows marked interstitial oedema and interstitial infiltrate in the connective tissue between renal tubules. Symptoms of acute interstitial nephritis include fever, rash, arthralgia, eosinophilia, mild renal impairment, and hypertension. Sterile pyuria and white cell casts are common findings in investigations.
Tubulointerstitial nephritis with uveitis (TINU) is a condition that typically affects young females. Symptoms of TINU include fever, weight loss, and painful, red eyes. Urinalysis is positive for leukocytes and protein.
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This question is part of the following fields:
- Renal System
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Question 11
Correct
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A 56-year-old man presents to the outpatient cardiology clinic complaining of fatigue and weight gain. He has been diagnosed with type II diabetes for 14 years and has been taking metformin to control his blood sugar levels. An echocardiogram reveals a globally dilated left ventricle with a reduced ejection fraction of approximately 30%, and his NT-proBNP level is 1256 (<125 pg/mL). The healthcare provider decides to initiate empagliflozin therapy due to its cardioprotective effects in patients with heart failure with reduced ejection fraction. What is the primary mechanism of action for this new medication?
Your Answer: Proximal convoluted tubule
Explanation:Glucose reabsorption within the nephron is mainly concentrated in the proximal convoluted tubule.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 12
Correct
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A 67-year-old man is being evaluated on the ward. He was admitted with community-acquired pneumonia and required IV antibiotics. The results of his blood tests taken this morning are as follows:
- Sodium (Na+): 143 mmol/L (135 - 145)
- Potassium (K+): 6.5 mmol/L (3.5 - 5.0)
- Bicarbonate: 25 mmol/L (22 - 29)
- Urea: 5.5 mmol/L (2.0 - 7.0)
- Creatinine: 115 µmol/L (55 - 120)
An urgent ECG is ordered, which reveals peaked T waves and a loss of P waves.
What is the immediate course of action for this patient?Your Answer: IV calcium gluconate
Explanation:The correct treatment for stabilizing the cardiac membrane in a patient with hyperkalaemia and ECG changes, such as peaked T waves and loss of P waves, is IV calcium gluconate. This is the first-line treatment option, as it can effectively stabilize the cardiac membrane and prevent arrhythmias. Other treatment options, such as calcium resonium, combined insulin/dextrose infusion, and nebulised salbutamol, can be used to treat hyperkalaemia, but only after IV calcium gluconate has been given.
Managing Hyperkalaemia: A Step-by-Step Guide
Hyperkalaemia is a serious condition that can lead to life-threatening arrhythmias if left untreated. To manage hyperkalaemia, it is important to address any underlying factors that may be contributing to the condition, such as acute kidney injury, and to stop any aggravating drugs, such as ACE inhibitors. Treatment can be categorised based on the severity of the hyperkalaemia, which is classified as mild, moderate, or severe based on the patient’s potassium levels.
ECG changes are also important in determining the appropriate management for hyperkalaemia. Peaked or ‘tall-tented’ T waves, loss of P waves, broad QRS complexes, and a sinusoidal wave pattern are all associated with hyperkalaemia and should be evaluated in all patients with new hyperkalaemia.
The principles of treatment modalities for hyperkalaemia include stabilising the cardiac membrane, shifting potassium from extracellular to intracellular fluid compartments, and removing potassium from the body. IV calcium gluconate is used to stabilise the myocardium, while insulin/dextrose infusion and nebulised salbutamol can be used to shift potassium from the extracellular to intracellular fluid compartments. Calcium resonium, loop diuretics, and dialysis can be used to remove potassium from the body.
In practical terms, all patients with severe hyperkalaemia or ECG changes should receive emergency treatment, including IV calcium gluconate to stabilise the myocardium and insulin/dextrose infusion to shift potassium from the extracellular to intracellular fluid compartments. Other treatments, such as nebulised salbutamol, may also be used to temporarily lower serum potassium levels. Further management may involve stopping exacerbating drugs, treating any underlying causes, and lowering total body potassium through the use of calcium resonium, loop diuretics, or dialysis.
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This question is part of the following fields:
- Renal System
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Question 13
Correct
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A 20-year-old man is brought to the Emergency Department in an unconscious state, lying in a pool of blood with several stab wounds in his abdomen. How does the physiological compensatory mechanism differ in the short-term for a venous bleed versus an arterial bleed?
Your Answer: A venous bleed causes reduced preload before reducing blood pressure and being detected by baroreceptors whilst an arterial bleed causes an instant blood pressure drop
Explanation:A venous bleed is compensated for in a less direct manner compared to an arterial bleed. The reduction in preload caused by a venous bleed results in a decrease in cardiac output and subsequently, blood pressure. Baroreceptors detect this drop in blood pressure and trigger a physiological compensation response.
In contrast, an arterial bleed causes an immediate drop in blood pressure, which is detected directly by baroreceptors.
Both types of bleeding result in increased levels of angiotensin II and a heightened thirst drive. However, these compensatory mechanisms take longer to take effect than the immediate response triggered by baroreceptors.
Understanding Bleeding and its Effects on the Body
Bleeding, even if it is of a small volume, triggers a response in the body that causes generalised splanchnic vasoconstriction. This response is mediated by the activation of the sympathetic nervous system. The process of vasoconstriction is usually enough to maintain renal perfusion and cardiac output if the volume of blood lost is small. However, if greater volumes of blood are lost, the renin angiotensin system is activated, resulting in haemorrhagic shock.
The body’s physiological measures can restore circulating volume if the source of bleeding ceases. Ongoing bleeding, on the other hand, will result in haemorrhagic shock. Blood loss is typically quantified by the degree of shock produced, which is determined by parameters such as blood loss volume, pulse rate, blood pressure, respiratory rate, urine output, and symptoms. Understanding the effects of bleeding on the body is crucial in managing and treating patients who experience blood loss.
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This question is part of the following fields:
- Renal System
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Question 14
Correct
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A 15-year-old teenage boy comes to see his General Practitioner with swelling in his left scrotum. He reports no pain or other symptoms. During examination in a supine position, the GP notes that the left testicle is smaller than the right and there are no abnormal masses on either side. The GP diagnoses the patient with a varicocele, which is caused by increased hydrostatic pressure in the venous plexus of the left scrotum. The question is, where does the left testicular (gonadal) vein drain into?
Your Answer: Left renal vein
Explanation:The left renal vein receives drainage from the left testicular vein, while the common iliac and internal iliac veins do not receive any blood from the testicles. The internal iliac veins collect blood from the pelvic internal organs and join the external iliac vein, which drains blood from the legs, to form the common iliac vein. On the other hand, the right testicular vein directly drains into the inferior vena cava since it is situated to the right of the midline. The great saphenous veins, which are located superficially, collect blood from the toes.
Scrotal Problems: Epididymal Cysts, Hydrocele, and Varicocele
Epididymal cysts are the most frequent cause of scrotal swellings seen in primary care. They are usually found posterior to the testicle and separate from the body of the testicle. Epididymal cysts may be associated with polycystic kidney disease, cystic fibrosis, or von Hippel-Lindau syndrome. Diagnosis is usually confirmed by ultrasound, and management is typically supportive. However, surgical removal or sclerotherapy may be attempted for larger or symptomatic cysts.
Hydrocele refers to the accumulation of fluid within the tunica vaginalis. They can be communicating or non-communicating. Communicating hydroceles are common in newborn males and usually resolve within the first few months of life. Non-communicating hydroceles are caused by excessive fluid production within the tunica vaginalis. Hydroceles may develop secondary to epididymo-orchitis, testicular torsion, or testicular tumors. Diagnosis may be clinical, but ultrasound is required if there is any doubt about the diagnosis or if the underlying testis cannot be palpated. Management depends on the severity of the presentation, and further investigation, such as ultrasound, is usually warranted to exclude any underlying cause such as a tumor.
Varicocele is an abnormal enlargement of the testicular veins. They are usually asymptomatic but may be important as they are associated with infertility. Varicoceles are much more common on the left side and are classically described as a bag of worms. Diagnosis is made through ultrasound with Doppler studies. Management is usually conservative, but occasionally surgery is required if the patient is troubled by pain. There is ongoing debate regarding the effectiveness of surgery to treat infertility.
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This question is part of the following fields:
- Renal System
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Question 15
Incorrect
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Which one of the following statements are not typically true in hypokalaemia?
Your Answer: Chronic vomiting may increase renal potassium losses
Correct Answer: It often accompanies acidosis
Explanation:Potassium depletion can occur through the gastrointestinal tract or the kidneys. Chronic vomiting is less likely to cause potassium loss than diarrhea because gastric secretions contain less potassium than lower GI secretions. However, if vomiting leads to metabolic alkalosis, renal potassium wasting may occur as the body excretes potassium instead of hydrogen ions. Conversely, potassium depletion can result in acidic urine.
Hypokalemia is often associated with metabolic alkalosis due to two factors. Firstly, common causes of metabolic alkalosis, such as vomiting and diuretics, directly cause loss of H+ and K+ (via aldosterone), leading to hypokalemia. Secondly, hypokalemia can cause metabolic alkalosis through three mechanisms. Firstly, it causes a transcellular shift where K+ leaves and H+ enters cells, raising extracellular pH. Secondly, it causes an intracellular acidosis in the proximal tubules, promoting ammonium production and excretion. Thirdly, in the presence of hypokalemia, hydrogen secretion in the proximal and distal tubules increases, leading to further reabsorption of HCO3-. Overall, this results in an increase in net acid excretion.
Understanding Hypokalaemia and its Causes
Hypokalaemia is a condition characterized by low levels of potassium in the blood. Potassium and hydrogen ions are competitors, and as potassium levels decrease, more hydrogen ions enter the cells. Hypokalaemia can occur with either alkalosis or acidosis. In cases of alkalosis, hypokalaemia may be caused by vomiting, thiazide and loop diuretics, Cushing’s syndrome, or Conn’s syndrome. On the other hand, hypokalaemia with acidosis may be caused by diarrhoea, renal tubular acidosis, acetazolamide, or partially treated diabetic ketoacidosis.
It is important to note that magnesium deficiency may also cause hypokalaemia. In such cases, normalizing potassium levels may be difficult until the magnesium deficiency has been corrected. Understanding the causes of hypokalaemia can help in its diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 16
Correct
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Jill, who is in her mid-30s, has just completed a half marathon and is now dehydrated. The decreased perfusion pressure in her kidneys is detected by baroreceptors, leading to the activation of the renin-angiotensin-aldosterone system (RAAS). As a result, renin cleaves angiotensinogen to angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme (ACE). What effect does angiotensin II have on the arteriole that branches off from the renal artery and carries blood away from the glomerulus? And how does this impact Jill's glomerular filtration rate (GFR)?
Your Answer: Vasoconstriction - increases GFR
Explanation:Angiotensin II causes vasoconstriction of the efferent arteriole, which increases the pressure difference between the afferent and efferent arterioles. This increase in pressure leads to an increase in filtration pressure and thus an increase in GFR. Therefore, efferent arteriole constriction increases GFR.
Reabsorption and Secretion in Renal Function
In renal function, reabsorption and secretion play important roles in maintaining homeostasis. The filtered load is the amount of a substance that is filtered by the glomerulus and is determined by the glomerular filtration rate (GFR) and the plasma concentration of the substance. The excretion rate is the amount of the substance that is eliminated in the urine and is determined by the urine flow rate and the urine concentration of the substance. Reabsorption occurs when the filtered load is greater than the excretion rate, and secretion occurs when the excretion rate is greater than the filtered load.
The reabsorption rate is the difference between the filtered load and the excretion rate, and the secretion rate is the difference between the excretion rate and the filtered load. Reabsorption and secretion can occur in different parts of the nephron, including the proximal tubule, loop of Henle, distal tubule, and collecting duct. These processes are regulated by various hormones and signaling pathways, such as aldosterone, antidiuretic hormone (ADH), and atrial natriuretic peptide (ANP).
Overall, reabsorption and secretion are important mechanisms for regulating the composition of the urine and maintaining fluid and electrolyte balance in the body. Dysfunction of these processes can lead to various renal disorders, such as diabetes insipidus, renal tubular acidosis, and Fanconi syndrome.
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This question is part of the following fields:
- Renal System
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Question 17
Incorrect
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A 30-year-old man presents to the emergency department with complaints of abdominal pain, nausea, and vomiting for a few hours. He has a history of type 1 diabetes mellitus, which is managed with insulin. He admits to running out of his insulin a few days ago. On examination, his temperature is 37.8ºC, pulse is 120/min, respirations are 25/min, and blood pressure is 100/70 mmHg. Dry mucous membranes are noted, and he has a fruity odour on his breath.
The following laboratory results are obtained:
Hb 142 g/L Male: (135-180)
Female: (115 - 160)
Platelets 250 * 109/L (150 - 400)
WBC 11.2 * 109/L (4.0 - 11.0)
Na+ 138 mmol/L (135 - 145)
K+ 5.2 mmol/L (3.5 - 5.0)
Urea 2.8 mmol/L (2.0 - 7.0)
Creatinine 110 µmol/L (55 - 120)
Glucose 28 mmol/L (4 - 7)
Which of the following laboratory findings is most likely to be seen in this patient?Your Answer: PH 7.5; pCO2 2.3 kPa; Anion Gap 25
Correct Answer: PH 7.1; pCO2 2.3 kPa; Anion Gap 21
Explanation:The patient is experiencing diabetic ketoacidosis, which results in a raised anion gap metabolic acidosis. To determine the correct answer, we must eliminate options with a normal or raised pH (7.4 and 7.5), as well as those with respiratory acidosis (as the patient has an increased respiratory rate and should have a low pCO2). The anion gap is also a crucial factor, with a normal range of 3 to 16. Therefore, the correct option is the one with an anion gap of 21.
Understanding Metabolic Acidosis
Metabolic acidosis is a condition that can be classified based on the anion gap, which is calculated by subtracting the sum of chloride and bicarbonate from the sum of sodium and potassium. The normal range for anion gap is 10-18 mmol/L. If a question provides the chloride level, it may be an indication to calculate the anion gap.
Hyperchloraemic metabolic acidosis is a type of metabolic acidosis with a normal anion gap. It can be caused by gastrointestinal bicarbonate loss, prolonged diarrhea, ureterosigmoidostomy, fistula, renal tubular acidosis, drugs like acetazolamide, ammonium chloride injection, and Addison’s disease. On the other hand, raised anion gap metabolic acidosis is caused by lactate, ketones, urate, acid poisoning, and other factors.
Lactic acidosis is a type of metabolic acidosis that is caused by high lactate levels. It can be further classified into two types: lactic acidosis type A, which is caused by sepsis, shock, hypoxia, and burns, and lactic acidosis type B, which is caused by metformin. Understanding the different types and causes of metabolic acidosis is important in diagnosing and treating the condition.
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This question is part of the following fields:
- Renal System
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Question 18
Correct
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A 9-year-old girl was brought to the clinic by her father who has been worried about increasing 'swelling around her eyes and legs' over the past few weeks. She is otherwise healthy. Upon further inquiry, her father reports no blood in her urine but noticed that it is more foamy than usual. A urinalysis shows severe proteinuria. The girl is referred for a kidney biopsy and eventually started on prednisolone based on the suspected diagnosis. What is the most probable result of the biopsy?
Your Answer: Podocyte effacement with electron microscopy
Explanation:The patient’s symptoms suggest that they may be suffering from nephrotic syndrome, which is characterized by periorbital and peripheral edema, as well as severe proteinuria. In young children, the most common cause of nephrotic syndrome is Minimal Change Disease, which can be identified through podocyte effacement on biopsy using electron microscopy. Fortunately, most cases of this disease in young children respond well to steroid treatment. Other potential diagnoses include membranous glomerulonephritis, Goodpasture syndrome, and focal segmental glomerulosclerosis.
Minimal change disease is a condition that typically presents as nephrotic syndrome, with children accounting for 75% of cases and adults accounting for 25%. While most cases are idiopathic, a cause can be found in around 10-20% of cases, such as drugs like NSAIDs and rifampicin, Hodgkin’s lymphoma, thymoma, or infectious mononucleosis. The pathophysiology of the disease involves T-cell and cytokine-mediated damage to the glomerular basement membrane, resulting in polyanion loss and a reduction of electrostatic charge, which increases glomerular permeability to serum albumin.
The features of minimal change disease include nephrotic syndrome, normotension (hypertension is rare), and highly selective proteinuria, where only intermediate-sized proteins like albumin and transferrin leak through the glomerulus. Renal biopsy shows normal glomeruli on light microscopy, while electron microscopy shows fusion of podocytes and effacement of foot processes.
Management of minimal change disease involves oral corticosteroids, which are effective in 80% of cases. For steroid-resistant cases, cyclophosphamide is the next step. The prognosis for the disease is generally good, although relapse is common. Roughly one-third of patients have just one episode, one-third have infrequent relapses, and one-third have frequent relapses that stop before adulthood.
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This question is part of the following fields:
- Renal System
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Question 19
Correct
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A 65-year-old man visits the haemofiltration unit thrice a week for treatment. What is responsible for detecting alterations in salt concentrations, such as sodium chloride, in normally functioning kidneys and adjusting the glomerular filtration rate accordingly?
Your Answer: Macula densa
Explanation:The macula densa is a specialized area of columnar tubule cells located in the final part of the ascending loop of Henle. These cells are in contact with the afferent arteriole and play a crucial role in detecting the concentration of sodium chloride in the convoluted tubules and ascending loop of Henle. This detection is affected by the glomerular filtration rate (GFR), which is increased by an increase in blood pressure. When the macula densa detects high sodium chloride levels, it releases ATP and adenosine, which constrict the afferent arteriole and lower GFR. Conversely, when low sodium chloride levels are detected, the macula densa releases nitric oxide, which acts as a vasodilator. The macula densa can also increase renin production from the juxtaglomerular cells.
Juxtaglomerular cells are smooth muscle cells located mainly in the walls of the afferent arteriole. They act as baroreceptors to detect changes in blood pressure and can secrete renin.
Mesangial cells are located at the junction of the afferent and efferent arterioles and, together with the juxtaglomerular cells and the macula densa, form the juxtaglomerular apparatus.
Podocytes, which are modified simple squamous epithelial cells with foot-like projections, make up the innermost layer of the Bowman’s capsule surrounding the glomerular capillaries. They assist in glomerular filtration.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 20
Correct
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A 59-year-old man comes to the GP complaining of lower back pain, weight loss, an abdominal mass, and visible haematuria. The GP eliminates the possibility of a UTI and refers him through a 2-week wait pathway. An ultrasound reveals a tumour, and a biopsy confirms renal cell carcinoma. From which part of the kidney does his cancer originate?
Your Answer: Proximal renal tubular epithelium
Explanation:Renal cell carcinoma originates from the proximal renal tubular epithelium, while the other options, such as blood vessels, distal renal tubular epithelium, and glomerular basement membrane, are all parts of the kidney but not the site of origin for renal cell carcinoma. Transitional cell carcinoma, on the other hand, arises from the transitional cells in the lining of the renal pelvis.
Renal cell cancer, also known as hypernephroma, is a primary renal neoplasm that accounts for 85% of cases. It originates from the proximal renal tubular epithelium and is commonly associated with smoking and conditions such as von Hippel-Lindau syndrome and tuberous sclerosis. The clear cell subtype is the most prevalent, comprising 75-85% of tumors.
Renal cell cancer is more common in middle-aged men and may present with classical symptoms such as haematuria, loin pain, and an abdominal mass. Other features include endocrine effects, such as the secretion of erythropoietin, parathyroid hormone-related protein, renin, and ACTH. Metastases are present in 25% of cases at presentation, and paraneoplastic syndromes such as Stauffer syndrome may also occur.
The T category criteria for renal cell cancer are based on tumor size and extent of invasion. Management options include partial or total nephrectomy, depending on the tumor size and extent of disease. Patients with a T1 tumor are typically offered a partial nephrectomy, while alpha-interferon and interleukin-2 may be used to reduce tumor size and treat metastases. Receptor tyrosine kinase inhibitors such as sorafenib and sunitinib have shown superior efficacy compared to interferon-alpha.
In summary, renal cell cancer is a common primary renal neoplasm that is associated with various risk factors and may present with classical symptoms and endocrine effects. Management options depend on the extent of disease and may include surgery and targeted therapies.
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This question is part of the following fields:
- Renal System
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Question 21
Correct
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Which one of the following changes are not typically seen in established dehydration?
Your Answer: Decreased serum urea to creatinine ratio
Explanation:The diagnosis of dehydration can be complex, with laboratory characteristics being a key factor to consider.
Pre-Operative Fluid Management Guidelines
Proper fluid management is crucial in preparing patients for surgery. The British Consensus guidelines on IV fluid therapy for Adult Surgical patients (GIFTASUP) and NICE (CG174 December 2013) have provided recommendations for pre-operative fluid management. These guidelines suggest the use of Ringer’s lactate or Hartmann’s for resuscitation or replacement of fluids, instead of 0.9% N. Saline due to the risk of hyperchloraemic acidosis. For maintenance fluids, 4%/0.18% dextrose saline or 5% dextrose should be used. Patients should not be nil by mouth for more than two hours, and carbohydrate-rich drinks should be given 2-3 hours before surgery. Mechanical bowel preparation should be avoided, but if used, simultaneous administration of Hartmann’s or Ringer’s lactate should be considered.
In cases of excessive fluid loss from vomiting, a crystalloid with potassium replacement should be given. Hartmann’s or Ringer lactate should be given for diarrhoea, ileostomy, ileus, obstruction, or sodium losses secondary to diuretics. High-risk patients should receive fluids and inotropes, and pre or operative hypovolaemia should be detected using flow-based measurements or clinical evaluation. In cases of blood loss or infection causing hypovolaemia, a balanced crystalloid or colloid should be used until blood is available. If IV fluid resuscitation is needed, crystalloids containing sodium in the range of 130-154 mmol/l should be used, with a bolus of 500 ml over less than 15 minutes. These guidelines aim to ensure that patients are properly hydrated and prepared for surgery, reducing the risk of complications and improving outcomes.
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This question is part of the following fields:
- Renal System
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Question 22
Correct
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A 65-year-old man presents to the emergency department with a 4-hour history of palpitations. He has been experiencing vomiting and diarrhoea for the past few days and feels increasingly lethargic. The patient has a medical history of type 2 diabetes mellitus and chronic kidney disease.
The following routine blood tests are taken:
- Hb 150 g/L (135-180)
- Platelets 308 * 109/L (150 - 400)
- WBC 12.4 * 109/L (4.0 - 11.0)
- Na+ 139 mmol/L (135 - 145)
- K+ 7.1 mmol/L (3.5 - 5.0)
- Urea 12.6 mmol/L (2.0 - 7.0)
- Creatinine 204 µmol/L (55 - 120)
- CRP 56 mg/L (< 5)
The patient's ECG shows sinus tachycardia and tall tented T waves.
What is the most appropriate initial management for this patient?Your Answer: Calcium gluconate
Explanation:To stabilize the cardiac membrane in a patient with hyperkalemia and ECG changes, the priority is to administer intravenous calcium gluconate. This is because hyperkalemia can lead to life-threatening arrhythmias and cardiac arrest if left untreated. ECG changes associated with hyperkalemia include tall tented T waves, P wave flattening and prolongation, and broad QRS complexes. Haemofiltration is generally reserved for refractory hyperkalemia, while insulin and dextrose infusion would treat hyperkalemia but not protect the heart from the risk of arrhythmia and death. Intravenous fluids play no role in the management of hyperkalemia or stabilizing the cardiac membrane.
Managing Hyperkalaemia: A Step-by-Step Guide
Hyperkalaemia is a serious condition that can lead to life-threatening arrhythmias if left untreated. To manage hyperkalaemia, it is important to address any underlying factors that may be contributing to the condition, such as acute kidney injury, and to stop any aggravating drugs, such as ACE inhibitors. Treatment can be categorised based on the severity of the hyperkalaemia, which is classified as mild, moderate, or severe based on the patient’s potassium levels.
ECG changes are also important in determining the appropriate management for hyperkalaemia. Peaked or ‘tall-tented’ T waves, loss of P waves, broad QRS complexes, and a sinusoidal wave pattern are all associated with hyperkalaemia and should be evaluated in all patients with new hyperkalaemia.
The principles of treatment modalities for hyperkalaemia include stabilising the cardiac membrane, shifting potassium from extracellular to intracellular fluid compartments, and removing potassium from the body. IV calcium gluconate is used to stabilise the myocardium, while insulin/dextrose infusion and nebulised salbutamol can be used to shift potassium from the extracellular to intracellular fluid compartments. Calcium resonium, loop diuretics, and dialysis can be used to remove potassium from the body.
In practical terms, all patients with severe hyperkalaemia or ECG changes should receive emergency treatment, including IV calcium gluconate to stabilise the myocardium and insulin/dextrose infusion to shift potassium from the extracellular to intracellular fluid compartments. Other treatments, such as nebulised salbutamol, may also be used to temporarily lower serum potassium levels. Further management may involve stopping exacerbating drugs, treating any underlying causes, and lowering total body potassium through the use of calcium resonium, loop diuretics, or dialysis.
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This question is part of the following fields:
- Renal System
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Question 23
Correct
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A 64-year-old man is seen in the endocrinology clinic for review of his type II diabetes. He is currently on metformin and gliclazide, but his HbA1c is 68 mmol/mol. To improve his glycaemic control, you plan to initiate empagliflozin as a third agent. What is the site of action of this medication to achieve its mechanism of action?
Your Answer: Proximal convoluted tubule of the nephron
Explanation:The proximal convoluted tubule of the nephron is where the majority of glucose reabsorption occurs. Empagliflozin, which inhibits the SGLT-2 receptor, prevents glucose reabsorption in this area. Insulin receptors are found throughout the body, not SGLT-2 receptors. The distal convoluted tubule regulates sodium, potassium, calcium, and pH, while the loop of Henle is involved in water resorption. Sulphonylureas act on pancreatic beta cells to increase insulin production and improve glucose metabolism.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 24
Incorrect
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In a patient with an ectopic kidney, where would you expect to find the adrenal gland situated?
Your Answer: In the pelvis
Correct Answer: In its usual position
Explanation:If the kidney is present, the adrenal gland will typically develop in its normal location instead of being absent.
The adrenal cortex, which secretes steroids, is derived from the mesoderm of the posterior abdominal wall and is first detected at 6 weeks’ gestation. The fetal cortex predominates throughout fetal life, with adult-type zona glomerulosa and fasciculata detected but making up only a small proportion of the gland. The adrenal medulla, which is responsible for producing adrenaline, is of ectodermal origin and arises from neural crest cells that migrate to the medial aspect of the developing cortex. The fetal adrenal gland is relatively large, but it rapidly regresses at birth, disappearing almost completely by age 1 year. By age 4-5 years, the permanent adult-type adrenal cortex has fully developed.
Anatomic anomalies of the adrenal gland may occur, such as agenesis of an adrenal gland being usually associated with ipsilateral agenesis of the kidney. Fused adrenal glands, whereby the two glands join across the midline posterior to the aorta, are also associated with a fused kidney. Adrenal hypoplasia can occur in two forms: hypoplasia or absence of the fetal cortex with a poorly formed medulla, or disorganized fetal cortex and medulla with no permanent cortex present. Adrenal heterotopia describes a normal adrenal gland in an abnormal location, such as within the renal or hepatic capsules. Accessory adrenal tissue, also known as adrenal rests, is most commonly located in the broad ligament or spermatic cord but can be found anywhere within the abdomen, and even intracranial adrenal rests have been reported.
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This question is part of the following fields:
- Renal System
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Question 25
Incorrect
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A 38-year-old male patient complains of a painless lump in his left testicle that he discovered during self-examination. Upon examination, a solid nodule is palpable in the left testicle, and ultrasound imaging reveals an irregular mass lesion. The patient's serum AFP and HCG levels are both normal. What is the probable diagnosis?
Your Answer: Yolk sac tumour
Correct Answer: Seminoma
Explanation:A seminoma is the most probable diagnosis for this man based on his age, symptoms, and normal levels of tumour markers. Teratomas and yolk sac tumours usually result in elevated AFP and HCG levels, which are not present in seminomas. Epididymo-orchitis does not cause painless irregular mass lesions.
Overview of Testicular Disorders
Testicular disorders can range from benign conditions to malignant tumors. Testicular cancer is the most common malignancy in men aged 20-30 years, with germ-cell tumors accounting for 95% of cases. Seminomas are the most common subtype, while non-seminomatous germ cell tumors include teratoma, yolk sac tumor, choriocarcinoma, and mixed germ cell tumors. Risk factors for testicular cancer include cryptorchidism, infertility, family history, Klinefelter’s syndrome, and mumps orchitis. The most common presenting symptom is a painless lump, but pain, hydrocele, and gynecomastia may also be present.
Benign testicular disorders include epididymo-orchitis, which is an acute inflammation of the epididymis often caused by bacterial infection. Testicular torsion, which results in testicular ischemia and necrosis, is most common in males aged between 10 and 30. Hydrocele presents as a mass that transilluminates and may occur as a result of a patent processus vaginalis in children. Treatment for these conditions varies, with orchidectomy being the primary treatment for testicular cancer. Surgical exploration is necessary for testicular torsion, while epididymo-orchitis and hydrocele may require medication or surgical procedures depending on the severity of the condition.
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This question is part of the following fields:
- Renal System
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Question 26
Correct
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A 6-year-old girl is brought to her pediatrician by her father. Her father reports that for the past 5 days, she has been experiencing swelling in her lower limbs. The girl is otherwise healthy, has not had any recent illnesses, and her blood pressure during the visit was normal. The results of her urinalysis are as follows:
Leucocytes: Negative
Nitrites: Negative
Urobilinogen: Negative
Proteins: 3+
Blood: Negative
Ketones: Negative
Glucose: Negative
What is the most probable diagnosis?Your Answer: Minimal change disease
Explanation:The boy’s symptoms are typical of nephrotic syndrome, which is characterized by a triad of proteinuria, hypoalbuminaemia, and oedema. Oedema is usually seen in the lower limbs, and proteinuria may cause frothy urine. Minimal change disease, focal segmental glomerulosclerosis, and membranous nephropathy are examples of nephrotic syndrome. Minimal change disease is a common cause of nephrotic syndrome, and it is characterized by effacement of the podocyte foot processes, which increases the permeability of the glomerular basement membrane and causes proteinuria.
It is important to differentiate nephrotic syndrome from nephritic syndrome, which is characterized by the presence of protein and blood in the urine. Nephritic syndrome typically presents with haematuria, oliguria, and hypertension. Alport syndrome is not a correct answer as it causes nephritic syndrome, and it is a genetic condition that affects kidney function, hearing, and vision. IgA nephropathy is also an incorrect answer as it causes nephritic syndrome and is typically associated with upper respiratory tract infections. A careful history is required to distinguish it from post-streptococcal glomerulonephritis, another cause of nephritic syndrome that occurs after a streptococcal infection.
Understanding Nephrotic Syndrome and its Presentation
Nephrotic syndrome is a condition characterized by a triad of symptoms, namely proteinuria, hypoalbuminaemia, and oedema. Proteinuria refers to the presence of excessive protein in the urine, typically exceeding 3g in a 24-hour period. Hypoalbuminaemia is a condition where the levels of albumin in the blood fall below 30g/L. Oedema, on the other hand, is the accumulation of fluid in the body tissues, leading to swelling.
Nephrotic syndrome is associated with the loss of antithrombin-III, proteins C and S, and an increase in fibrinogen levels, which increases the risk of thrombosis. Additionally, the loss of thyroxine-binding globulin leads to a decrease in total thyroxine levels, although free thyroxine levels remain unaffected.
The diagram below illustrates the different types of glomerulonephritides and how they typically present. Understanding the presentation of nephrotic syndrome and its associated risks is crucial in the diagnosis and management of this condition.
[Insert diagram here]
Overall, nephrotic syndrome is a complex condition that requires careful management to prevent complications. By understanding its presentation and associated risks, healthcare professionals can provide appropriate treatment and support to patients with this condition.
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This question is part of the following fields:
- Renal System
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Question 27
Incorrect
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A 67-year-old man is attending the urology clinic and receiving goserelin for his metastatic prostate cancer. Can you explain the drug's mechanism of action?
Your Answer: Inhibits 5 alpha reductase enzyme
Correct Answer: Overstimulation of GnRH receptors
Explanation:GnRH agonists used in the treatment of prostate cancer can paradoxically lead to lower LH levels in the long term. This is because chronic use of these agonists can result in overstimulation of GnRH receptors, which in turn disrupts endogenous hormonal feedback systems. While initially stimulating the production of LH/FSH and subsequent androgen production, chronic use of GnRH agonists can cause negative feedback to suppress the release of gonadotropins, resulting in a significant decrease in serum testosterone levels. This mechanism can be thought of as switching on to switch off. It is important to note that inhibiting the 5 alpha-reductase enzyme and relaxing prostatic smooth muscle are not mechanisms of action for GnRH agonists, but rather for other medications used in the treatment of prostate conditions.
Prostate cancer management varies depending on the stage of the disease and the patient’s life expectancy and preferences. For localized prostate cancer (T1/T2), treatment options include active monitoring, watchful waiting, radical prostatectomy, and radiotherapy (external beam and brachytherapy). For localized advanced prostate cancer (T3/T4), options include hormonal therapy, radical prostatectomy, and radiotherapy. Patients may develop proctitis and are at increased risk of bladder, colon, and rectal cancer following radiotherapy for prostate cancer.
In cases of metastatic prostate cancer, reducing androgen levels is a key aim of treatment. A combination of approaches is often used, including anti-androgen therapy, synthetic GnRH agonist or antagonists, bicalutamide, cyproterone acetate, abiraterone, and bilateral orchidectomy. GnRH agonists, such as Goserelin (Zoladex), initially cause a rise in testosterone levels before falling to castration levels. To prevent a rise in testosterone, anti-androgens are often used to cover the initial therapy. GnRH antagonists, such as degarelix, are being evaluated to suppress testosterone while avoiding the flare phenomenon. Chemotherapy with docetaxel is also an option for the treatment of hormone-relapsed metastatic prostate cancer in patients who have no or mild symptoms after androgen deprivation therapy has failed, and before chemotherapy is indicated.
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This question is part of the following fields:
- Renal System
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Question 28
Correct
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A nephrologist is evaluating a 12-year-old boy who presented with general malaise and was found to have proteinuria and haematuria on urine dipstick by his primary care physician. Following a comprehensive assessment, the nephrologist orders a renal biopsy. The biopsy report reveals that the immunofluorescence of the sample showed a granular appearance. What is the probable diagnosis?
Your Answer: Post-streptococcal glomerulonephritis
Explanation:Post-streptococcal glomerulonephritis is a condition that typically occurs 7-14 days after an infection caused by group A beta-haemolytic Streptococcus, usually Streptococcus pyogenes. It is more common in young children and is caused by the deposition of immune complexes (IgG, IgM, and C3) in the glomeruli. Symptoms include headache, malaise, visible haematuria, proteinuria, oedema, hypertension, and oliguria. Blood tests may show a raised anti-streptolysin O titre and low C3, which confirms a recent streptococcal infection.
It is important to note that IgA nephropathy and post-streptococcal glomerulonephritis are often confused as they both can cause renal disease following an upper respiratory tract infection. Renal biopsy features of post-streptococcal glomerulonephritis include acute, diffuse proliferative glomerulonephritis with endothelial proliferation and neutrophils. Electron microscopy may show subepithelial ‘humps’ caused by lumpy immune complex deposits, while immunofluorescence may show a granular or ‘starry sky’ appearance.
Despite its severity, post-streptococcal glomerulonephritis carries a good prognosis.
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This question is part of the following fields:
- Renal System
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Question 29
Incorrect
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A 70-year-old male was admitted to the hospital due to delirium observed in the nursing home. Upon diagnosis, he was found to have a lower respiratory tract infection which progressed to sepsis. During his stay in the ICU, he was discovered to have severe hyponatremia. The medical team has prescribed tolvaptan along with other medications.
What is the mechanism of action of tolvaptan?Your Answer: Vasopressin V2 receptor agonist
Correct Answer: Vasopressin V2 receptor antagonist
Explanation:Tolvaptan is a drug that blocks the action of vasopressin at the V2 receptor, which reduces water absorption and increases aquaresis without sodium loss. Vasopressin is a hormone that regulates water balance in the body.
Autosomal dominant polycystic kidney disease (ADPKD) is a commonly inherited kidney disease that affects 1 in 1,000 Caucasians. The disease is caused by mutations in two genes, PKD1 and PKD2, which produce polycystin-1 and polycystin-2 respectively. ADPKD type 1 accounts for 85% of cases, while ADPKD type 2 accounts for 15% of cases. ADPKD type 1 is caused by a mutation in the PKD1 gene on chromosome 16, while ADPKD type 2 is caused by a mutation in the PKD2 gene on chromosome 4. ADPKD type 1 tends to present with renal failure earlier than ADPKD type 2.
To screen for ADPKD in relatives of affected individuals, an abdominal ultrasound is recommended. The diagnostic criteria for ultrasound include the presence of two cysts, either unilateral or bilateral, if the individual is under 30 years old. If the individual is between 30-59 years old, two cysts in both kidneys are required for diagnosis. If the individual is over 60 years old, four cysts in both kidneys are necessary for diagnosis.
For some patients with ADPKD, tolvaptan, a vasopressin receptor 2 antagonist, may be an option to slow the progression of cyst development and renal insufficiency. However, NICE recommends tolvaptan only for adults with ADPKD who have chronic kidney disease stage 2 or 3 at the start of treatment, evidence of rapidly progressing disease, and if the company provides it with the agreed discount in the patient access scheme.
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This question is part of the following fields:
- Renal System
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Question 30
Incorrect
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A 55-year-old man, who has a history of type 2 diabetes, is prescribed losartan for his hypertension due to the development of a dry cough from ramipril. Losartan works by inhibiting the activity of a substance that acts on the AT1 receptor.
What accurately characterizes the function of this substance?Your Answer: Decreases filtration fraction through vasoconstriction of the afferent arteriole of the glomerulus to preserve glomerular filtration rate (GFR)
Correct Answer: Increases filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus to preserve GFR
Explanation:Angiotensin II is responsible for increasing the filtration fraction by constricting the efferent arteriole of the glomerulus, which helps to maintain the glomerular filtration rate (GFR). This mechanism has been found to slow down the progression of diabetic nephropathy. AT1 receptor blockers such as azilsartan, candesartan, and olmesartan can also block the action of Ang II. Desmopressin activates aquaporin, which is mainly located in the collecting duct of the kidneys. Norepinephrine and epinephrine, not Ang II, can cause vasoconstriction of the afferent arteriole of the glomerulus.
The renin-angiotensin-aldosterone system is a complex system that regulates blood pressure and fluid balance in the body. The adrenal cortex is divided into three zones, each producing different hormones. The zona glomerulosa produces mineralocorticoids, mainly aldosterone, which helps regulate sodium and potassium levels in the body. Renin is an enzyme released by the renal juxtaglomerular cells in response to reduced renal perfusion, hyponatremia, and sympathetic nerve stimulation. It hydrolyses angiotensinogen to form angiotensin I, which is then converted to angiotensin II by angiotensin-converting enzyme in the lungs. Angiotensin II has various actions, including causing vasoconstriction, stimulating thirst, and increasing proximal tubule Na+/H+ activity. It also stimulates aldosterone and ADH release, which causes retention of Na+ in exchange for K+/H+ in the distal tubule.
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This question is part of the following fields:
- Renal System
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