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  • Question 1 - A 46-year-old patient visits his doctor 5 days after his last appointment, worried...

    Incorrect

    • A 46-year-old patient visits his doctor 5 days after his last appointment, worried about passing very small amounts of urine for the past 4 days. He was prescribed gentamicin for an infection during his last visit. The doctor suspects gentamicin-induced nephrotoxicity and conducts an examination, finding no abnormalities and normal blood pressure and temperature. The patient's fractional excretion of urine is greater than 4%, and a urine sample is sent to the lab for microscopy, culture, and sensitivity. What would be observed on microscopy if the doctor's suspicion is correct?

      Your Answer: Red cell casts

      Correct Answer: Brown granular casts

      Explanation:

      The clinical significance of various laboratory findings is summarized in the table below:

      Laboratory Finding Clinical Significance

      Elevated creatinine and BUN Indicates impaired kidney function
      Low serum albumin Indicates malnutrition or liver disease
      Elevated liver enzymes Indicates liver damage or disease
      Elevated glucose Indicates diabetes or impaired glucose tolerance
      Elevated potassium Indicates kidney dysfunction or medication side effect
      Elevated sodium Indicates dehydration or excessive sodium intake
      Elevated nitrites Indicates urinary tract infection
      Elevated white blood cells Indicates infection or inflammation
      Elevated red blood cells Indicates dehydration or kidney disease
      Elevated platelets Indicates clotting disorder or inflammation

      Different Types of Urinary Casts and Their Significance

      Urine contains various types of urinary casts that can provide important information about the underlying condition of the patient. Hyaline casts, for instance, are composed of Tamm-Horsfall protein that is secreted by the distal convoluted tubule. These casts are commonly seen in normal urine, after exercise, during fever, or with loop diuretics. On the other hand, brown granular casts in urine are indicative of acute tubular necrosis.

      In prerenal uraemia, the urinary sediment appears ‘bland’, which means that there are no significant abnormalities in the urine. Lastly, red cell casts are associated with nephritic syndrome, which is a condition characterized by inflammation of the glomeruli in the kidneys. By analyzing the type of urinary casts present in the urine, healthcare professionals can diagnose and manage various kidney diseases and disorders. Proper identification and interpretation of urinary casts can help in the early detection and treatment of kidney problems.

    • This question is part of the following fields:

      • Renal System
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  • Question 2 - A 55-year-old woman who underwent laparoscopic cholecystectomy is being evaluated on postoperative day...

    Correct

    • A 55-year-old woman who underwent laparoscopic cholecystectomy is being evaluated on postoperative day 2. She reports multiple episodes of vomiting and passing urine only once since the operation. Her medical history includes poorly controlled hypertension on dual therapy. She is currently taking fenoldopam, ACE inhibitors, calcium channel blockers, atorvastatin, and paracetamol. On physical examination, she has dry mucous membranes and a BMI of 31 kg/m². Her vital signs show a mean arterial pressure of 80 mmHg and a heart rate of 110 beats per minute. Laboratory results reveal:

      Na+ 130 mmol/L (135 - 145)
      K+ 5.1 mmol/L (3.5 - 5.0)
      Creatinine 160 µmol/L (55 - 120)

      What is the most important medication that should be discontinued in this patient?

      Your Answer: ACE inhibitors

      Explanation:

      In cases of acute kidney injury (AKI), it is crucial to identify and treat the underlying cause. However, it is important to note that ACE inhibitors should be discontinued as they can worsen renal function by causing efferent arteriolar vasodilation, leading to a decrease in GFR. On the other hand, atorvastatin should not be stopped as it does not accumulate and worsen renal function, but frequent monitoring is necessary. If AKI is caused by rhabdomyolysis, then statins should be immediately discontinued. Calcium channel blockers do not exacerbate renal impairment, but it is advisable to reduce the dose and withhold them if clinical signs appear. Fenoldopam, on the other hand, does not impair kidney function but rather increases blood flow to the renal cortex and medullary regions by decreasing systemic vascular resistance.

      Acute kidney injury (AKI) is a condition where there is a reduction in renal function following an insult to the kidneys. It was previously known as acute renal failure and can result in long-term impaired kidney function or even death. AKI can be caused by prerenal, intrinsic, or postrenal factors. Patients with chronic kidney disease, other organ failure/chronic disease, a history of AKI, or who have used drugs with nephrotoxic potential are at an increased risk of developing AKI. To prevent AKI, patients at risk may be given IV fluids or have certain medications temporarily stopped.

      The kidneys are responsible for maintaining fluid balance and homeostasis, so a reduced urine output or fluid overload may indicate AKI. Symptoms may not be present in early stages, but as renal failure progresses, patients may experience arrhythmias, pulmonary and peripheral edema, or features of uraemia. Blood tests such as urea and electrolytes can be used to detect AKI, and urinalysis and imaging may also be necessary.

      Management of AKI is largely supportive, with careful fluid balance and medication review. Loop diuretics and low-dose dopamine are not recommended, but hyperkalaemia needs prompt treatment to avoid life-threatening arrhythmias. Renal replacement therapy may be necessary in severe cases. Patients with suspected AKI secondary to urinary obstruction require prompt review by a urologist, and specialist input from a nephrologist is required for cases where the cause is unknown or the AKI is severe.

    • This question is part of the following fields:

      • Renal System
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  • Question 3 - A 75-year-old man is brought to the Emergency Department after he was found...

    Correct

    • A 75-year-old man is brought to the Emergency Department after he was found on the floor at home following a fall. He reports being immobile and staying on the floor overnight, but was otherwise healthy with no chest pain or dizziness. He is slightly confused and dehydrated, and complains of hip pain. However, further investigation reveals no fracture, but elevated levels of creatine kinase, creatinine, and urea. He takes simvastatin and amlodipine for hypercholesterolaemia and hypertension.

      What is the most probable cause of this sudden kidney injury?

      Your Answer: Acute tubular necrosis

      Explanation:

      The most common cause of acute kidney injury is acute tubular necrosis, which may be caused by various factors. In this case, the patient is likely to have rhabdomyolysis due to muscle damage from a fall. The release of myoglobin from damaged muscles can cause renal ischaemia, leading to acute tubular necrosis. Treatment involves addressing the cause of renal ischaemia and administering intravenous fluids to manage dehydration.

      While statins can cause rhabdomyolysis, the patient’s history suggests direct muscle trauma as the cause. Malignancy is a possibility, but the absence of prior symptoms and sudden onset of symptoms after a fall make it less likely than muscle trauma.

      IgA nephropathy typically presents with haematuria following an upper respiratory tract infection, but this is not relevant to the current case.

      Acute tubular necrosis (ATN) is a common cause of acute kidney injury (AKI) that affects the functioning of the kidney by causing necrosis of renal tubular epithelial cells. The condition is reversible in its early stages if the cause is removed. The two main causes of ATN are ischaemia and nephrotoxins, which can be caused by shock, sepsis, aminoglycosides, myoglobin secondary to rhabdomyolysis, radiocontrast agents, and lead. The features of ATN include raised urea, creatinine, and potassium levels, as well as muddy brown casts in the urine. Histopathological features include tubular epithelium necrosis, dilatation of the tubules, and necrotic cells obstructing the tubule lumen. ATN has three phases: the oliguric phase, the polyuric phase, and the recovery phase.

    • This question is part of the following fields:

      • Renal System
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  • Question 4 - A 25-year-old suffers a groin stab wound resulting in hypovolaemic shock. What would...

    Incorrect

    • A 25-year-old suffers a groin stab wound resulting in hypovolaemic shock. What would be the probable observation on examining his urine?

      Your Answer: Decreased specific gravity

      Correct Answer: Increased specific gravity

      Explanation:

      When blood pressure drops below the level at which the kidney can regulate its blood flow, hypovolemic shock can lead to a reduction in renal blood flow. This can cause an increase in specific gravity as the body tries to retain water to maintain blood volume.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 5 - A 75-year-old man presents to the emergency department with shortness of breath. He...

    Incorrect

    • A 75-year-old man presents to the emergency department with shortness of breath. He has no known medical conditions but is known to have a 80 pack-year smoking history. He reports that he has had a cough for the past six months, bringing up white sputum. An arterial blood gas reveals the following:

      pH 7.30 mmol/L (7.35-7.45)
      PaO2 9.1 kPa (10.5 - 13.5)
      PaCO2 6.2 kPa (5.1 - 5.6)
      Bicarbonate 34 mmol/L (22 - 29)

      What process is likely to occur in this patient?

      Your Answer: Excretion of bicarbonate

      Correct Answer: Increased secretion of erythropoietin

      Explanation:

      Erythropoietin is produced by the kidney when there is a lack of oxygen in the body’s cells. Based on the patient’s smoking history and symptoms, it is probable that she has chronic obstructive pulmonary disorder (COPD). The type II respiratory failure and respiratory acidosis partially compensated by metabolic alkalosis suggest long-term changes. This chronic hypoxia triggers the secretion of erythropoietin, which increases the production of red blood cells, leading to polycythemia.

      The accumulation of digestive enzymes in the pancreas is a characteristic of cystic fibrosis, but it is unlikely to be a new diagnosis in a 73-year-old woman. Moreover, cystic fibrosis patients typically have an isolated/compensated metabolic alkalosis on ABG, not a metabolic alkalosis attempting to correct a respiratory acidosis.

      Excretion of bicarbonate is incorrect because bicarbonate would be secreted to further correct the respiratory acidosis, making this option incorrect.

      Mucociliary system damage is the process that occurs in bronchiectasis, which would likely present with purulent sputum rather than white sputum. Additionally, there is no medical history to suggest the development of bronchiectasis.

      Understanding Erythropoietin and its Side-Effects

      Erythropoietin is a type of growth factor that stimulates the production of red blood cells. It is produced by the kidneys in response to low oxygen levels in the body. Erythropoietin is commonly used to treat anemia associated with chronic kidney disease and chemotherapy. However, it is important to note that there are potential side-effects associated with its use.

      Some of the side-effects of erythropoietin include accelerated hypertension, bone aches, flu-like symptoms, skin rashes, and urticaria. In some cases, patients may develop pure red cell aplasia, which is caused by antibodies against erythropoietin. Additionally, erythropoietin can increase the risk of thrombosis due to raised PCV levels. Iron deficiency may also occur as a result of increased erythropoiesis.

      There are several reasons why patients may not respond to erythropoietin therapy, including iron deficiency, inadequate dosage, concurrent infection or inflammation, hyperparathyroid bone disease, and aluminum toxicity. It is important for healthcare providers to monitor patients closely for these potential side-effects and adjust treatment as necessary.

    • This question is part of the following fields:

      • Renal System
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  • Question 6 - A 94-year-old male is admitted to the emergency department after being found on...

    Incorrect

    • A 94-year-old male is admitted to the emergency department after being found on the floor for several hours due to a fall. What blood test is crucial to perform in a patient who has been immobile for an extended period of time?

      Your Answer: Troponin

      Correct Answer: Creatine kinase

      Explanation:

      When an elderly person remains in bed for an extended period, the pressure on their muscles can cause muscle death and rhabdomyolysis. This leads to the breakdown of skeletal muscles and the release of muscle contents into the bloodstream, resulting in hyperkalemia. This is a medical emergency that can cause cardiac arrest.

      Therefore, it is crucial to test for creatine kinase in patients who have been bedridden for a long time to diagnose rhabdomyolysis. Creatine kinase levels will be elevated and may reach several tens of thousands.

      To investigate the cause of the fall, other blood tests may be necessary, such as calcium to check for dehydration, sodium to detect hyponatremia, and troponin to determine if there was a cardiac ischemic event.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 7 - An aged male patient suffers from seizures and loses consciousness. Central pontine myelinolysis...

    Correct

    • An aged male patient suffers from seizures and loses consciousness. Central pontine myelinolysis is diagnosed. What substance in the blood, when rapidly corrected from low levels, causes this condition?

      Your Answer: Sodium

      Explanation:

      Central pontine myelinolysis is commonly caused by rapid correction of hyponatraemia, but it is not associated with the other options. Rapid correction of hypokalaemia may result in hyperkalaemia-induced arrhythmias, while rapid correction of hypocalcaemia may cause hypercalcaemia-related symptoms such as bone pain, renal/biliary colic, abdominal pain, and psychiatric symptoms (known as bones, stones, moans, and groans). Hypochloraemia is typically asymptomatic and not routinely monitored in clinical practice. Rapid correction of hypomagnesaemia may lead to hypermagnesaemia-induced weakness, nausea and vomiting, arrhythmias, and decreased tendon reflexes.

      Hyponatremia is a condition where the sodium levels in the blood are too low. If left untreated, it can lead to cerebral edema and brain herniation. Therefore, it is important to identify and treat hyponatremia promptly. The treatment plan depends on various factors such as the duration and severity of hyponatremia, symptoms, and the suspected cause. Over-rapid correction can lead to osmotic demyelination syndrome, which is a serious complication.

      Initial steps in treating hyponatremia involve ruling out any errors in the test results and reviewing medications that may cause hyponatremia. For chronic hyponatremia without severe symptoms, the treatment plan varies based on the suspected cause. If it is hypovolemic, normal saline may be given as a trial. If it is euvolemic, fluid restriction and medications such as demeclocycline or vaptans may be considered. If it is hypervolemic, fluid restriction and loop diuretics or vaptans may be considered.

      For acute hyponatremia with severe symptoms, patients require close monitoring in a hospital setting. Hypertonic saline is used to correct the sodium levels more quickly than in chronic cases. Vaptans, which act on V2 receptors, can be used but should be avoided in patients with hypovolemic hyponatremia and those with underlying liver disease.

      It is important to avoid over-correction of severe hyponatremia as it can lead to osmotic demyelination syndrome. Symptoms of this condition include dysarthria, dysphagia, paralysis, seizures, confusion, and coma. Therefore, sodium levels should only be raised by 4 to 6 mmol/L in a 24-hour period to prevent this complication.

    • This question is part of the following fields:

      • Renal System
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  • Question 8 - A 95-year-old man is discovered collapsed in his residence and is transported to...

    Correct

    • A 95-year-old man is discovered collapsed in his residence and is transported to the hospital. Upon examination, he is diagnosed with dehydration and hypotension, prompting the release of renin by the juxtaglomerular cells. What is the mechanism of action of renin?

      Your Answer: Hydrolyse angiotensinogen to form angiotensin I

      Explanation:

      Angiotensin I is formed when renin breaks down angiotensinogen, which is a process that occurs within the renin-angiotensin-aldosterone system and is facilitated by juxtaglomerular cells.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 9 - A 6-year-old girl visits her pediatrician with significant swelling around her eyes. Her...

    Correct

    • A 6-year-old girl visits her pediatrician with significant swelling around her eyes. Her mother reports that the patient has been passing foamy urine lately.

      Upon conducting a urine dipstick test, the pediatrician observes proteinuria +++ with no other anomalies.

      The pediatrician suspects that the patient may have minimal change disease leading to nephrotic syndrome.

      What is the association of this condition with light microscopy?

      Your Answer: Normal glomerular architecture

      Explanation:

      In minimal change disease, light microscopy typically shows no abnormalities.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 10 - A 65-year-old woman with chronic kidney failure has been instructed by her nephrologist...

    Correct

    • A 65-year-old woman with chronic kidney failure has been instructed by her nephrologist to adhere to a 'renal diet'. She visits you to gain more knowledge about this.

      What is typically recommended to individuals with chronic kidney disease?

      Your Answer: Low potassium diet

      Explanation:

      Dietary Recommendations for Chronic Kidney Disease Patients

      Chronic kidney disease patients are recommended to follow a specific diet that is low in protein, phosphate, sodium, and potassium. This dietary advice is given to reduce the strain on the kidneys, as these substances are typically excreted by the kidneys. By limiting the intake of these nutrients, patients can help slow the progression of their kidney disease and manage their symptoms more effectively. It is important for patients to work closely with their healthcare provider or a registered dietitian to ensure they are meeting their nutritional needs while following these dietary restrictions. With proper guidance and adherence to this diet, patients with chronic kidney disease can improve their overall health and quality of life.

    • This question is part of the following fields:

      • Renal System
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  • Question 11 - A 40-year-old man arrives at the emergency department with low blood pressure after...

    Correct

    • A 40-year-old man arrives at the emergency department with low blood pressure after a car crash. What is the mechanism by which angiotensin II increases the filtration fraction in the kidney?

      Your Answer: Vasoconstriction of the efferent glomerular arteriole

      Explanation:

      Angiotensin II helps maintain GFR by increasing the filtration fraction through vasoconstriction of the efferent arteriole of the glomerulus. Despite its vasoconstrictive effect on the glomerular arteries, angiotensin II has a greater impact on the efferent arteriole, leading to an increase in glomerular pressure and filtration fraction.

      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.

    • This question is part of the following fields:

      • Renal System
      3.6
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  • Question 12 - A 54-year-old man visits the outpatient clinic complaining of feeling generally unwell with...

    Incorrect

    • A 54-year-old man visits the outpatient clinic complaining of feeling generally unwell with increased diarrhoea and vomiting for the past week. He has a medical history of hypertension and type 2 diabetes mellitus and is currently taking amlodipine, candesartan, doxazosin, metformin, gliclazide, and insulin.

      The following investigations were conducted:

      Results today 3 months ago Reference ranges
      Na+ 137 mmol/L 133 mmol/L (135 - 145)
      K+ 6.1 mmol/L 3.6 mmol/L (3.5 - 5.0)
      Urea 8.9 mmol/L 4.5 mmol/L (2.0 - 7.0)
      Creatinine 155 µmol/L 65 µmol/L (55 - 120)
      eGFR 35 mL/min/1.73m² 90 mL/min/1.73m² (> 60)

      Which medication should be discontinued?

      Your Answer: Amlodipine

      Correct Answer: Candesartan

      Explanation:

      In cases of acute kidney injury, it is important to identify and treat the underlying cause while preventing further deterioration. However, certain medications must be discontinued, including angiotensin-converting enzyme inhibitors or angiotensin receptor blockers, NSAIDs, and diuretics. Therefore, candesartan, an angiotensin receptor blocker, should be stopped in this patient. On the other hand, amlodipine, a calcium channel blocker, and doxazosin, an alpha antagonist, are safe to continue in patients with acute kidney injury.

      Acute kidney injury (AKI) is a condition where there is a reduction in renal function following an insult to the kidneys. It was previously known as acute renal failure and can result in long-term impaired kidney function or even death. AKI can be caused by prerenal, intrinsic, or postrenal factors. Patients with chronic kidney disease, other organ failure/chronic disease, a history of AKI, or who have used drugs with nephrotoxic potential are at an increased risk of developing AKI. To prevent AKI, patients at risk may be given IV fluids or have certain medications temporarily stopped.

      The kidneys are responsible for maintaining fluid balance and homeostasis, so a reduced urine output or fluid overload may indicate AKI. Symptoms may not be present in early stages, but as renal failure progresses, patients may experience arrhythmias, pulmonary and peripheral edema, or features of uraemia. Blood tests such as urea and electrolytes can be used to detect AKI, and urinalysis and imaging may also be necessary.

      Management of AKI is largely supportive, with careful fluid balance and medication review. Loop diuretics and low-dose dopamine are not recommended, but hyperkalaemia needs prompt treatment to avoid life-threatening arrhythmias. Renal replacement therapy may be necessary in severe cases. Patients with suspected AKI secondary to urinary obstruction require prompt review by a urologist, and specialist input from a nephrologist is required for cases where the cause is unknown or the AKI is severe.

    • This question is part of the following fields:

      • Renal System
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  • Question 13 - What electrolyte imbalance is probable in a patient experiencing diarrhea and a palpable...

    Correct

    • What electrolyte imbalance is probable in a patient experiencing diarrhea and a palpable soft mass during digital rectal examination?

      Your Answer: Hypokalaemia

      Explanation:

      Rectal secretions from large villous adenomas of the rectum can cause hypokalaemia due to their high potassium content, which is a result of the marked secretory activity of the adenomas.

      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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      • Renal System
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  • Question 14 - In a patient with an ectopic kidney, where would you expect to find...

    Correct

    • In a patient with an ectopic kidney, where would you expect to find the adrenal gland situated?

      Your 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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      • Renal System
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  • Question 15 - Which one of the following structures is not located behind the left kidney?...

    Correct

    • Which one of the following structures is not located behind the left kidney?

      Your Answer: 10th rib

      Explanation:

      Renal Anatomy: Understanding the Structure and Relations of the Kidneys

      The kidneys are two bean-shaped organs located in a deep gutter alongside the vertebral bodies. They measure about 11cm long, 5cm wide, and 3 cm thick, with the left kidney usually positioned slightly higher than the right. The upper pole of both kidneys approximates with the 11th rib, while the lower border is usually alongside L3. The kidneys are surrounded by an outer cortex and an inner medulla, which contains pyramidal structures that terminate at the renal pelvis into the ureter. The renal sinus lies within the kidney and contains branches of the renal artery, tributaries of the renal vein, major and minor calyces, and fat.

      The anatomical relations of the kidneys vary depending on the side. The right kidney is in direct contact with the quadratus lumborum, diaphragm, psoas major, and transversus abdominis, while the left kidney is in direct contact with the quadratus lumborum, diaphragm, psoas major, transversus abdominis, stomach, pancreas, spleen, and distal part of the small intestine. Each kidney and suprarenal gland is enclosed within a common layer of investing fascia, derived from the transversalis fascia, which is divided into anterior and posterior layers (Gerotas fascia).

      At the renal hilum, the renal vein lies most anteriorly, followed by the renal artery (an end artery), and the ureter lies most posteriorly. Understanding the structure and relations of the kidneys is crucial in diagnosing and treating renal diseases and disorders.

    • This question is part of the following fields:

      • Renal System
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  • Question 16 - A fourth year medical student presents to their GP with haemoptysis following a...

    Incorrect

    • A fourth year medical student presents to their GP with haemoptysis following a recent mild flu-like illness. Upon urinalysis, microscopic haematuria is detected. The GP suspects Goodpasture's syndrome and refers the student to the acute medical unit at the nearby hospital. What type of hypersensitivity reaction is Goodpasture's syndrome an example of?

      Your Answer: Type 1

      Correct Answer: Type 2

      Explanation:

      The Gell and Coombs classification of hypersensitivity reactions categorizes reactions into four types. Type 2 reactions involve the binding of IgG and IgM to a cell, resulting in cell death. Examples of type 2 reactions include Goodpasture syndrome, haemolytic disease of the newborn, and rheumatic fever.

      Allergic rhinitis is an instance of a type 1 (immediate) reaction, which is IgE mediated. It is a hypersensitivity to a previously harmless substance.

      Type 3 reactions are mediated by immune complexes, with rheumatoid arthritis being an example of a type 3 hypersensitivity reaction.

      Type 4 (delayed) reactions are mediated by T lymphocytes and cause contact dermatitis.

      Anti-glomerular basement membrane (GBM) disease, previously known as Goodpasture’s syndrome, is a rare form of small-vessel vasculitis that is characterized by both pulmonary haemorrhage and rapidly progressive glomerulonephritis. This condition is caused by anti-GBM antibodies against type IV collagen and is more common in men, with a bimodal age distribution. Goodpasture’s syndrome is associated with HLA DR2.

      The features of this disease include pulmonary haemorrhage and rapidly progressive glomerulonephritis, which can lead to acute kidney injury. Nephritis can result in proteinuria and haematuria. Renal biopsy typically shows linear IgG deposits along the basement membrane, while transfer factor is raised secondary to pulmonary haemorrhages.

      Management of anti-GBM disease involves plasma exchange (plasmapheresis), steroids, and cyclophosphamide. One of the main complications of this condition is pulmonary haemorrhage, which can be exacerbated by factors such as smoking, lower respiratory tract infection, pulmonary oedema, inhalation of hydrocarbons, and young males.

    • This question is part of the following fields:

      • Renal System
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  • Question 17 - A 63-year-old man is seen in the oncology clinic. He is being monitored...

    Correct

    • A 63-year-old man is seen in the oncology clinic. He is being monitored for known breast cancer. His recent mammogram and biopsy suggest an increased disease burden. It is decided to initiate Tamoxifen therapy while awaiting a mastectomy.

      What is the mechanism of action of this new medication?

      Your Answer: Androgen receptor blocker

      Explanation:

      Bicalutamide is a medication that blocks the androgen receptor and is commonly used to treat prostate cancer. Abiraterone, on the other hand, is an androgen synthesis inhibitor that is prescribed to patients with metastatic prostate cancer who have not responded to androgen deprivation therapy. GnRH agonists like goserelin can also be used to treat prostate cancer by reducing the release of gonadotrophins and inhibiting androgen production. While cyproterone acetate is a steroidal anti-androgen, it is not as commonly used as non-steroidal anti-androgens like bicalutamide.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 18 - A 35-year-old female patient complains of chronic flank pain. Her family history reveals...

    Incorrect

    • A 35-year-old female patient complains of chronic flank pain. Her family history reveals a brother with similar symptoms and a mother who died from a subarachnoid haemorrhage. Bilateral renal ultrasound shows multiple cysts. Which chromosome is most likely to be affected in this genetic disorder?

      Your Answer: 3

      Correct Answer: 16

      Explanation:

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 19 - A 65-year-old man comes in with symptoms related to his lower urinary tract...

    Correct

    • A 65-year-old man comes in with symptoms related to his lower urinary tract and is given the option to take a PSA test. What factor could potentially affect the accuracy of his PSA level?

      Your Answer: Vigorous exercise in the past 48 hours

      Explanation:

      Understanding PSA Testing for Prostate Cancer

      Prostate specific antigen (PSA) is an enzyme produced by the prostate gland that has become an important marker for prostate cancer. However, there is still much debate about its usefulness as a screening tool. The NHS Prostate Cancer Risk Management Programme (PCRMP) has published guidelines on how to handle requests for PSA testing in asymptomatic men. While a recent European trial showed a reduction in prostate cancer deaths, there is also a high risk of over-diagnosis and over-treatment. As a result, the National Screening Committee has decided not to introduce a prostate cancer screening programme yet, but rather allow men to make an informed choice.

      PSA levels may be raised by various factors, including benign prostatic hyperplasia, prostatitis, ejaculation, vigorous exercise, urinary retention, and instrumentation of the urinary tract. However, PSA levels are not always a reliable indicator of prostate cancer. For example, around 20% of men with prostate cancer have a normal PSA level, while around 33% of men with a PSA level of 4-10 ng/ml will be found to have prostate cancer. To add greater meaning to a PSA level, age-adjusted upper limits and monitoring changes in PSA level over time (PSA velocity or PSA doubling time) are used. The PCRMP recommends age-adjusted upper limits for PSA levels, with a limit of 3.0 ng/ml for men aged 50-59 years, 4.0 ng/ml for men aged 60-69 years, and 5.0 ng/ml for men over 70 years old.

    • This question is part of the following fields:

      • Renal System
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  • Question 20 - A 55-year-old male presents to the emergency department with a high fever and...

    Correct

    • A 55-year-old male presents to the emergency department with a high fever and fatigue. He does not have any history to offer. On examination, he is noted to have splinter haemorrhages and conjunctival pallor. His observations show him to be pyrexial at 39°C. A pansystolic murmur is audible throughout the praecordium, and an echocardiogram reveals vegetations. He is diagnosed with infective endocarditis and initiated on a triple antibiotic therapy of gentamicin, vancomycin and amoxicillin. The following U&E results are noted at admission:

      Na+ 140 mmol/L (135 - 145)
      K+ 4.0 mmol/L (3.5 - 5.0)
      Bicarbonate 25 mmol/L (22 - 29)
      Urea 4.0 mmol/L (2.0 - 7.0)
      Creatinine 75 µmol/L (55 - 120)

      However, following three days of inpatient treatment, the patient becomes anuric. A repeat set of U&Es reveal the following:

      Na+ 145 mmol/L (135 - 145)
      K+ 5.0 mmol/L (3.5 - 5.0)
      Bicarbonate 25 mmol/L (22 - 29)
      Urea 12.0 mmol/L (2.0 - 7.0)
      Creatinine 150 µmol/L (55 - 120)

      What is the likely mechanism of gentamicin causing this patient’s kidney injury?

      Your Answer: Renal cell apoptosis

      Explanation:

      AKI can be attributed to gentamicin due to its ability to induce apoptosis in renal cells. Therefore, patients who are prescribed gentamicin should undergo frequent monitoring of their renal function and drug concentration levels. While there are other potential causes of acute kidney injury, none of them are linked to aminoglycoside antibiotics.

      Understanding the Difference between Acute Tubular Necrosis and Prerenal Uraemia

      Acute kidney injury can be caused by various factors, including prerenal uraemia and acute tubular necrosis. It is important to differentiate between the two to determine the appropriate treatment. Prerenal uraemia occurs when the kidneys hold on to sodium to preserve volume, leading to decreased blood flow to the kidneys. On the other hand, acute tubular necrosis is caused by damage to the kidney tubules, which can be due to various factors such as toxins, infections, or ischemia.

      To differentiate between the two, several factors can be considered. In prerenal uraemia, the urine sodium level is typically less than 20 mmol/L, while in acute tubular necrosis, it is usually greater than 40 mmol/L. The urine osmolality is also higher in prerenal uraemia, typically above 500 mOsm/kg, while in acute tubular necrosis, it is usually below 350 mOsm/kg. The fractional sodium excretion is less than 1% in prerenal uraemia, while it is greater than 1% in acute tubular necrosis. Additionally, the response to fluid challenge is typically good in prerenal uraemia, while it is poor in acute tubular necrosis.

      Other factors that can help differentiate between the two include the serum urea:creatinine ratio, fractional urea excretion, urine:plasma osmolality, urine:plasma urea, specific gravity, and urine sediment. By considering these factors, healthcare professionals can accurately diagnose and treat acute kidney injury.

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      • Renal System
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  • Question 21 - A 49-year-old woman is having surgery to remove an adrenal adenoma on her...

    Correct

    • A 49-year-old woman is having surgery to remove an adrenal adenoma on her left side. During the procedure, the superior adrenal artery is damaged and begins to bleed. What is the origin of this vessel?

      Your Answer: Inferior phrenic artery

      Explanation:

      The inferior phrenic artery gives rise to the superior adrenal artery.

      Adrenal Gland Anatomy

      The adrenal glands are located superomedially to the upper pole of each kidney. The right adrenal gland is posteriorly related to the diaphragm, inferiorly related to the kidney, medially related to the vena cava, and anteriorly related to the hepato-renal pouch and bare area of the liver. On the other hand, the left adrenal gland is postero-medially related to the crus of the diaphragm, inferiorly related to the pancreas and splenic vessels, and anteriorly related to the lesser sac and stomach.

      The arterial supply of the adrenal glands is through the superior adrenal arteries from the inferior phrenic artery, middle adrenal arteries from the aorta, and inferior adrenal arteries from the renal arteries. The right adrenal gland drains via one central vein directly into the inferior vena cava, while the left adrenal gland drains via one central vein into the left renal vein.

      In summary, the adrenal glands are small but important endocrine glands located above the kidneys. They have a unique blood supply and drainage system, and their location and relationships with other organs in the body are crucial for their proper functioning.

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      • Renal System
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  • Question 22 - A 64-year-old man is seen in the endocrinology clinic for review of his...

    Correct

    • 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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      • Renal System
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  • Question 23 - A 56-year-old man with end stage diabetic nephropathy is undergoing evaluation for a...

    Correct

    • A 56-year-old man with end stage diabetic nephropathy is undergoing evaluation for a renal transplant. In terms of HLA matching between donor and recipient, which HLA antigen is the most crucial to match?

      Your Answer: DR

      Explanation:

      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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      • Renal System
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  • Question 24 - A 20-year-old patient visits their GP complaining of non-specific malaise. The patient has...

    Correct

    • A 20-year-old patient visits their GP complaining of non-specific malaise. The patient has a medical history of recurrent haematuria during childhood with infections and fever, as well as bilateral mild sensorineural hearing loss. Due to frequent moves between countries, the patient has never had continuous medical care. Further investigations reveal proteinuria and haematuria, leading to a referral to secondary care and a subsequent renal biopsy. The biopsy results show splitting of the lamina densa on electron microscopy.

      What is the most common mode of inheritance for this likely diagnosis?

      Your Answer: X-linked dominant

      Explanation:

      Alport’s syndrome is a genetic disorder that is typically inherited in an X-linked dominant pattern. It is caused by a defect in the gene responsible for producing type IV collagen, which leads to an abnormal glomerular-basement membrane (GBM). The disease is more severe in males, with females rarely developing renal failure. Symptoms usually present in childhood and may include microscopic haematuria, progressive renal failure, bilateral sensorineural deafness, lenticonus, retinitis pigmentosa, and splitting of the lamina densa seen on electron microscopy. In some cases, an Alport’s patient with a failing renal transplant may have anti-GBM antibodies, leading to a Goodpasture’s syndrome-like picture. Diagnosis can be made through molecular genetic testing, renal biopsy, or electron microscopy. In around 85% of cases, the syndrome is inherited in an X-linked dominant pattern, while 10-15% of cases are inherited in an autosomal recessive fashion, with rare autosomal dominant variants existing.

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      • Renal System
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  • Question 25 - During your placement on a gastro ward, a patient in their late 60s...

    Incorrect

    • During your placement on a gastro ward, a patient in their late 60s develops excessive diarrhea. Can you identify the location in the gastrointestinal tract where most of the water is absorbed?

      Your Answer: Ileum

      Correct Answer: Jejunum

      Explanation:

      The absorption of water in the gastrointestinal tract is facilitated by the absorption of ions across cell membranes. The majority of water is absorbed in the small intestine, particularly in the jejunum.

      Water Absorption in the Human Body

      Water absorption in the human body is a crucial process that occurs in the small bowel and colon. On average, a person ingests up to 2000ml of liquid orally within a 24-hour period. Additionally, gastrointestinal secretions contribute to a further 8000ml of fluid entering the small bowel. The process of intestinal water absorption is passive and is dependent on the solute load. In the jejunum, the active absorption of glucose and amino acids creates a concentration gradient that facilitates the flow of water across the membrane. On the other hand, in the ileum, most water is absorbed through facilitated diffusion, which involves the movement of water molecules with sodium ions.

      The colon also plays a significant role in water absorption, with approximately 150ml of water entering it daily. However, the colon can adapt and increase this amount following resection. Overall, water absorption is a complex process that involves various mechanisms and is essential for maintaining proper hydration levels in the body.

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      • Renal System
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  • Question 26 - A 28-year-old man is on day 9 of his cycle from Land's End...

    Correct

    • A 28-year-old man is on day 9 of his cycle from Land's End to John O'Groats. He made a wrong turn and ran out of fluids. After getting back on track, he found a shop and purchased a 2L bottle of water.

      Which part of the nephron is responsible for reabsorbing the majority of this water?

      Your Answer: Proximal tubule

      Explanation:

      The correct answer is the proximal tubule. This is where the majority of filtered water is reabsorbed, due to the osmotic force generated by Na+ reabsorption. Bowman’s capsule only allows for ultrafiltration, while the collecting duct allows for variable water reabsorption, but not to the same extent as the proximal tubule. The distal tubule also plays a role in Na+ reabsorption, but water reabsorption is dependent on this mechanism.

      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.

    • This question is part of the following fields:

      • Renal System
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  • Question 27 - A patient with compromised kidney function is given a new medication that is...

    Correct

    • A patient with compromised kidney function is given a new medication that is typically eliminated through renal excretion. What factors might impact the excretion of the medication?

      Your Answer: Diffusivity across the basement membrane and tubular secretion/reabsorption

      Explanation:

      The clearance of a substance in the kidneys is influenced by two important factors: diffusivity across the basement membrane and tubular secretion/reabsorption. Additionally, the Loop of Henle plays a crucial role in generating a significant osmotic gradient, while the primary function of the collecting duct is to facilitate the reabsorption of water.

      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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      • Renal System
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  • Question 28 - A 65-year-old man presents to the emergency department with a 4-hour history of...

    Correct

    • 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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      • Renal System
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  • Question 29 - A 65-year-old man comes to the clinic for a medication review. He reports...

    Correct

    • A 65-year-old man comes to the clinic for a medication review. He reports no negative effects and wishes to continue his current treatment. After conducting a blood test, you notice that his serum potassium level is slightly elevated. Which of the following frequently prescribed drugs is linked to an increase in serum potassium?

      Your Answer: Ramipril

      Explanation:

      Ramipril is the correct answer. Before starting ACE inhibitor therapy, a baseline potassium level is measured because these drugs can cause an increase in serum potassium.

      Loop diuretics like furosemide can cause hypokalaemia and hyponatraemia.

      Salbutamol does not lead to hyperkalaemia and can actually be used to lower serum potassium levels in emergency situations.

      Taking paracetamol within recommended doses does not affect potassium levels.

      Drugs and their Effects on Potassium Levels

      Many commonly prescribed drugs have the potential to alter the levels of potassium in the bloodstream. Some drugs can decrease the amount of potassium in the blood, while others can increase it.

      Drugs that can decrease serum potassium levels include thiazide and loop diuretics, as well as acetazolamide. On the other hand, drugs that can increase serum potassium levels include ACE inhibitors, angiotensin-2 receptor blockers, spironolactone, and potassium-sparing diuretics like amiloride and triamterene. Additionally, taking potassium supplements like Sando-K or Slow-K can also increase potassium levels in the blood.

      It’s important to note that the above list does not include drugs used to temporarily decrease serum potassium levels for patients with hyperkalaemia, such as salbutamol or calcium resonium.

      Overall, it’s crucial for healthcare providers to be aware of the potential effects of medications on potassium levels and to monitor patients accordingly.

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      • Renal System
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  • Question 30 - Which of the following medications can lead to hyperkalemia? ...

    Correct

    • Which of the following medications can lead to hyperkalemia?

      Your Answer: Heparin

      Explanation:

      Hyperkalaemia can be caused by both unfractionated and low-molecular weight heparin due to their ability to inhibit aldosterone secretion. Salbutamol is a known remedy for hyperkalaemia.

      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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      • Renal System
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SESSION STATS - PERFORMANCE PER SPECIALTY

Renal System (22/30) 73%
Passmed