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Question 1
Correct
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A 16-year-old boy is being evaluated for weight loss and increased thirst. During a urine dipstick test, one of the parameters showed a +++ result. In which part of the nephron does the resorption of this solute primarily occur?
Your Answer: Proximal convoluted tubule
Explanation:Glucose is primarily reabsorbed in the proximal convoluted tubule of the nephron. In individuals with type 1 diabetes, the level of circulating glucose exceeds the nephron’s capacity for reabsorption, resulting in glycosuria or glucose in the urine. The collecting duct system mainly reabsorbs water under the control of hormones such as ADH. The descending limb of the loop of Henle is primarily permeable to water, while the distal convoluted tubule mainly absorbs ions and water through active transport. The thick ascending limb of the loop of Henle is the main site of resorption for sodium, potassium, and chloride ions, creating a hypotonic filtrate.
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 2
Incorrect
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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 4
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.
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This question is part of the following fields:
- Renal System
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Question 3
Incorrect
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A patient in his 60s is recovering on the ward following a kidney transplant. Six days after the operation he still requires dialysis, however he is not in any pain and the graft was a very good HLA match from a deceased donor. His renal function test results are shown below.
Hb 93 g/L
Plts. 232 x 109
Na+ 151 mmol/l
K+ 5.7 mmol/l
Urea 7.9 mmol/l
eGFR 27 mL/min/1.73m2
What could be the probable reason for his abnormal renal function tests?Your Answer: Volume depletion
Correct Answer: Delayed graft function
Explanation:Delayed graft function (DGF) is a common form of acute renal failure that can occur following a kidney transplant. In this case, delayed graft function is the most likely explanation for the patient’s symptoms. It is not uncommon for patients to require continued dialysis after a transplant, especially if the donor was deceased. However, if the need for dialysis persists beyond 7 days, further investigations may be necessary. Other potential causes, such as Addison’s disease or hyper-acute graft rejection, are less likely based on the patient’s history and the characteristics of the transplant.
Complications Following Renal Transplant
Renal transplantation is a common procedure, but it is not without its complications. The most common technical complications are related to the ureteric anastomosis, and the warm ischaemic time is also important as graft survival is directly related to this. Long warm ischaemic times increase the risk of acute tubular necrosis, which can occur in all types of renal transplantation. Organ rejection is also a possibility at any phase following the transplantation process.
There are three types of organ rejection: hyperacute, acute, and chronic. Hyperacute rejection occurs immediately due to the presence of preformed antibodies, such as ABO incompatibility. Acute rejection occurs during the first six months and is usually T cell mediated, with tissue infiltrates and vascular lesions. Chronic rejection occurs after the first six months and is characterized by vascular changes, with myointimal proliferation leading to organ ischemia.
In addition to immunological complications, there are also technical complications that can arise following renal transplant. These include renal artery thrombosis, renal artery stenosis, renal vein thrombosis, urine leaks, and lymphocele. Each of these complications presents with specific symptoms and requires different treatments, ranging from immediate surgery to angioplasty or drainage techniques.
Overall, while renal transplantation can be a life-saving procedure, it is important to be aware of the potential complications and to monitor patients closely for any signs of rejection or technical issues.
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This question is part of the following fields:
- Renal System
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Question 4
Correct
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A 70-year-old male visits his GP complaining of increased difficulty in breathing. He has a history of left ventricular heart failure, and his symptoms suggest a worsening of his condition. The doctor prescribes spironolactone as a diuretic. What is the mechanism of action of this medication?
Your Answer: Aldosterone antagonist
Explanation:The mechanism of action of spironolactone involves blocking the aldosterone receptor in the distal tubules and collecting duct of the kidneys. In contrast, furosemide acts as a loop diuretic by inhibiting the sodium/potassium/2 chloride inhibitor in the loop of Henle, while acetazolamide functions as a carbonic anhydrase inhibitor.
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 5
Incorrect
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A 29-year-old female patient complains of dysuria and frequent urination for the past 3 days. She denies experiencing any vaginal discharge or heavy menstrual bleeding. Upon urine dipstick examination, leukocytes and nitrites are detected. A urine culture reveals the presence of a urease-producing bacteria identified as Proteus mirabilis. The patient is prescribed antibiotics for treatment.
What type of renal stones are patients at risk for developing with chronic and recurrent infections caused by this bacteria?Your Answer: Uric acid
Correct Answer: Ammonium magnesium phosphate (struvite)
Explanation:The formation of kidney stones is a common condition that involves the accumulation of mineral deposits in the kidneys. This condition is influenced by various risk factors such as low urine volume, dry weather conditions, and acidic pH levels. It is also closely linked to hyperuricemia, which is commonly associated with gout, as well as diseases that involve high cell turnover, such as leukemia.
Renal stones can be classified into different types based on their composition. Calcium oxalate stones are the most common, accounting for 85% of all calculi. These stones are formed due to hypercalciuria, hyperoxaluria, and hypocitraturia. They are radio-opaque and may also bind with uric acid stones. Cystine stones are rare and occur due to an inherited recessive disorder of transmembrane cystine transport. Uric acid stones are formed due to purine metabolism and may precipitate when urinary pH is low. Calcium phosphate stones are associated with renal tubular acidosis and high urinary pH. Struvite stones are formed from magnesium, ammonium, and phosphate and are associated with chronic infections. The pH of urine can help determine the type of stone present, with calcium phosphate stones forming in normal to alkaline urine, uric acid stones forming in acidic urine, and struvate stones forming in alkaline urine. Cystine stones form in normal urine pH.
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This question is part of the following fields:
- Renal System
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Question 6
Incorrect
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A 60-year-old man with chronic kidney disease secondary to diabetes is scheduled to undergo a contrast-enhanced CT scan for a suspected brain lesion. His latest eGFR is 51ml/min/1.73m2. After a multidisciplinary team discussion, it was decided that using contrast in the scan was in the patient's best interests, despite the increased risk of contrast-induced acute kidney injury. What would be the most suitable approach to minimize the risk of contrast-induced acute kidney injury in this situation?
Your Answer: Maintain tight glycaemic control by switching from metformin therapy to insulin therapy
Correct Answer: Offer IV hydration before and after infusion
Explanation:To reduce the risk of contrast-induced acute kidney injury in high-risk patients, NICE guidelines recommend administering sodium chloride at a rate of 1 mL/kg/hour for 12 hours before and after the procedure. While there is some evidence supporting the use of acetylcysteine via IV infusion, it is not strong enough to be recommended in the guidelines. In at-risk patients, it is important to discuss whether the contrast is necessary. Waiting for the patient’s eGFR to improve is not a realistic option in this scenario, as the patient has chronic kidney disease. While maintaining tight glycaemic control is important for long-term kidney function, it is less relevant in this setting. Potentially nephrotoxic medications such as NSAIDs should be temporarily stopped, and ACE inhibitor therapy should be considered for cessation in patients with an eGFR less than 40ml/min/1.73m2, according to NICE guidelines.
Contrast media nephrotoxicity is characterized by a 25% increase in creatinine levels within three days of receiving intravascular contrast media. This condition typically occurs between two to five days after administration and is more likely to affect patients with pre-existing renal impairment, dehydration, cardiac failure, or those taking nephrotoxic drugs like NSAIDs. Procedures that may cause contrast-induced nephropathy include CT scans with contrast and coronary angiography or percutaneous coronary intervention (PCI). Around 5% of patients who undergo PCI experience a temporary increase in plasma creatinine levels of more than 88 µmol/L.
To prevent contrast-induced nephropathy, intravenous 0.9% sodium chloride should be administered at a rate of 1 mL/kg/hour for 12 hours before and after the procedure. Isotonic sodium bicarbonate may also be used. While N-acetylcysteine was previously used, recent evidence suggests it is not effective. Patients at high risk for contrast-induced nephropathy should have metformin withheld for at least 48 hours and until their renal function returns to normal to avoid the risk of lactic acidosis.
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This question is part of the following fields:
- Renal System
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Question 7
Incorrect
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A 6-year-old girl is referred to the child assessment unit (CAU) for recurrent urinary tract infections. The paediatric consultant on CAU orders a group of investigations to find out the underlying cause.
What are the risk factors for UTIs in children, as the paediatrics trainee has asked the medical student?Your Answer: Double voiding
Correct Answer: Posterior urethral valves
Explanation:The risk of urinary tract infection is higher in individuals with posterior urethral valves.
Posterior urethral valves are a frequent cause of blockage in the lower urinary tract in males. They can be detected during prenatal ultrasound screenings. Due to the high pressure required for bladder emptying during fetal development, the child may experience damage to the renal parenchyma, resulting in renal impairment in 70% of boys upon diagnosis. Treatment involves the use of a bladder catheter, and endoscopic valvotomy is the preferred definitive treatment. Cystoscopic and renal follow-up is necessary.
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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 49-year-old man with a history of chronic alcohol abuse presents with abdominal distension and is diagnosed with decompensated alcoholic liver disease with ascites. The consultant initiates treatment with spironolactone to aid in the management of his ascites.
What is the mode of action of spironolactone?Your Answer: Inhibition of the mineralocorticoid receptor in the cortical collecting ducts
Explanation:Aldosterone antagonists function as diuretics by targeting the cortical collecting ducts.
By inhibiting the mineralocorticoid receptor in the cortical collecting ducts, spironolactone acts as an aldosterone antagonist.
Loop diuretics like furosemide work by blocking the sodium/potassium/chloride transporter in the loop of Henle.
Thiazide diuretics, such as bendroflumethiazide, block the sodium/chloride transporter in the distal convoluted tubules.
Carbonic anhydrase inhibitors, like dorzolamide, act on the proximal tubules.
Amiloride inhibits the epithelial sodium transporter in the distal convoluted tubules.
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 9
Incorrect
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A 49-year-old male presents to the GP for a routine blood check and follow-up. He has a medical history of angina, hypertension, asthma, and hyperlipidemia. Upon reviewing his medications, it is noted that he is taking fenofibrate, a drug that reduces triglyceride levels and increases the synthesis of high-density lipoprotein (HDL). What is the mechanism of action of this medication?
Your Answer: Reduction in the reabsorption of bile acids
Correct Answer: Activation of PPAR receptor resulting in increase lipoprotein lipase (LPL) activity
Explanation:Fibrates activate PPAR alpha receptors, which increase LPL activity and reduce triglyceride levels. These drugs are effective in lowering cholesterol.
Statins work by inhibiting HMG-CoA reductase, which reduces the mevalonate pathway and lowers cholesterol levels.
Niacin, also known as vitamin B3, inhibits hepatic diacylglycerol acyltransferase-2, which is necessary for triglyceride synthesis.
Bile acid sequestrants bind to bile salts, reducing the reabsorption of bile acids and lowering cholesterol levels.
Apolipoprotein E is a protein that plays a role in fat metabolism, specifically in removing chylomicron remnants.
Understanding Fibrates and Their Role in Managing Hyperlipidaemia
Fibrates are a class of drugs commonly used to manage hyperlipidaemia, a condition characterized by high levels of lipids in the blood. Specifically, fibrates are effective in reducing elevated triglyceride levels. This is achieved through the activation of PPAR alpha receptors, which in turn increases the activity of LPL, an enzyme responsible for breaking down triglycerides.
Despite their effectiveness, fibrates are not without side effects. Gastrointestinal side effects are common, and patients may experience symptoms such as nausea, vomiting, and diarrhea. Additionally, there is an increased risk of thromboembolism, a condition where a blood clot forms and blocks a blood vessel.
In summary, fibrates are a useful tool in managing hyperlipidaemia, particularly in cases where triglyceride levels are elevated. However, patients should be aware of the potential side effects and discuss any concerns with their healthcare provider.
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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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A 45-year-old man presents to the physician complaining of fatigue, dark urine, and swelling in his lower extremities that has been ongoing for the past two weeks. He has no significant medical history and is not taking any medications. He denies using tobacco, alcohol, or drugs. During the physical examination, symmetric pitting oedema is observed in his lower extremities, and his blood pressure is 132/83 mmHg with a pulse of 84/min.
Laboratory results reveal a urea level of 4mmol/L (2.0 - 7.0) and a creatinine level of 83 µmol/L (55 - 120). Urinalysis shows 4+ proteinuria and microscopic hematuria. Electron microscopy of the kidney biopsy specimen reveals dense deposits within the glomerular basement membrane, and immunofluorescence microscopy is positive for C3, not immunoglobulins.
What is the most likely pathophysiologic mechanism underlying this patient's condition?Your Answer: Anti- GBM antibodies
Correct Answer: Persistent activation of alternate complement pathway
Explanation:The cause of membranoproliferative glomerulonephritis, type 2, is persistent activation of the alternative complement pathway, which leads to kidney damage. This condition is characterized by IgG antibodies, known as C3 nephritic factor, that target C3 convertase. In contrast, Goodpasture’s syndrome is associated with anti-GBM antibodies, while rapidly progressive glomerulonephritis may involve cell-mediated injury. Immune complex-mediated glomerulopathies, such as SLE and post-streptococcal glomerulonephritis, are caused by circulating immune complexes, while non-immunologic kidney damage is seen in diabetic nephropathy and hypertensive nephropathy.
Understanding Membranoproliferative Glomerulonephritis
Membranoproliferative glomerulonephritis, also known as mesangiocapillary glomerulonephritis, is a kidney disease that can present as nephrotic syndrome, haematuria, or proteinuria. Unfortunately, it has a poor prognosis. There are three types of this disease, with type 1 accounting for 90% of cases. It is caused by cryoglobulinaemia and hepatitis C, and can be diagnosed through a renal biopsy that shows subendothelial and mesangium immune deposits of electron-dense material resulting in a ‘tram-track’ appearance under electron microscopy.
Type 2, also known as ‘dense deposit disease’, is caused by partial lipodystrophy and factor H deficiency. It is characterized by persistent activation of the alternative complement pathway, low circulating levels of C3, and the presence of C3b nephritic factor in 70% of cases. This factor is an antibody to alternative-pathway C3 convertase (C3bBb) that stabilizes C3 convertase. A renal biopsy for type 2 shows intramembranous immune complex deposits with ‘dense deposits’ under electron microscopy.
Type 3 is caused by hepatitis B and C. While steroids may be effective in managing this disease, it is important to note that the prognosis for all types of membranoproliferative glomerulonephritis is poor. Understanding the different types and their causes can help with diagnosis and management of this serious kidney disease.
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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 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 12
Correct
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At what level is the hilum of the right kidney located?
Your Answer: L1
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.
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This question is part of the following fields:
- Renal System
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Question 13
Incorrect
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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: Minimal change disease
Correct 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 14
Incorrect
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A 28-year-old woman with autosomal dominant polycystic kidney disease type 1 is seeking guidance from her general practitioner regarding family planning. She recently lost her father to a subarachnoid haemorrhage, which prompted her to undergo genetic testing to confirm her diagnosis. Despite her desire to start a family with her husband, she is worried about the possibility of passing on the renal disease to her children. On which chromosome is the genetic defect for this condition most commonly found?
Your Answer: X chromosome
Correct Answer: Chromosome 16
Explanation:The patient’s autosomal dominant polycystic kidney disease type 1 is not caused by a gene on chromosomes 13, 18, or 21. It is important to note that nondisjunction of these chromosomes can lead to other genetic disorders such as Patau syndrome, Edward’s syndrome, and Down’s syndrome. The chance of the patient passing on the autosomal dominant polycystic kidney disease type 1 to her children would depend on the inheritance pattern of the specific gene mutation causing the disease.
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 15
Incorrect
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A 22-year-old man is referred to a cardiologist by his family physician due to consistently high cholesterol levels in his blood tests. During the assessment, the cardiologist observes yellowish skin nodules around the patient's Achilles tendon and white outer regions of the iris. The cardiologist informs the patient that he has inherited the condition from his biological parents and that there is a 50% chance of passing it on to his offspring, regardless of his partner's status. The patient reports a paternal uncle who died at 31 due to a heart-related condition. The cardiologist recommends treatment to manage cholesterol levels and prevent future cardiovascular events. What is the most likely underlying pathology in this patient's condition?
Your Answer: Defective apolipoprotein E
Correct Answer: Defective low-density lipoprotein receptors
Explanation:The patient’s symptoms and signs suggest that they may have one of the familial dyslipidemias, likely familial hypercholesterolemia. This is supported by the presence of Achilles tendon xanthomas and corneal arcus in a relatively young patient, as well as the cardiologist’s statement that there is a 50% chance of inheritance if the mother is normal, indicating an autosomal dominant inheritance pattern. Familial hypercholesterolemia is caused by defective or absent LDL receptors.
Other familial dyslipidemias include dysbetalipoproteinemia, which is caused by defective apolipoprotein E and has an autosomal recessive inheritance pattern, hypertriglyceridemia, which is caused by overproduction of VLDL and has an autosomal dominant inheritance pattern, and hyperchylomicronemia, which is caused by deficiency of lipoprotein lipase or apolipoprotein C-II and has an autosomal recessive inheritance pattern. Hyperchylomicronemia is not associated with a higher risk of atherosclerosis, unlike the other forms of familial dyslipidemia.
Familial Hypercholesterolaemia: Causes, Diagnosis, and Management
Familial hypercholesterolaemia (FH) is a genetic condition that affects approximately 1 in 500 people. It is an autosomal dominant disorder that results in high levels of LDL-cholesterol, which can lead to early cardiovascular disease if left untreated. FH is caused by mutations in the gene that encodes the LDL-receptor protein.
To diagnose FH, NICE recommends suspecting it as a possible diagnosis in adults with a total cholesterol level greater than 7.5 mmol/l and/or a personal or family history of premature coronary heart disease. For children of affected parents, testing should be arranged by age 10 if one parent is affected and by age 5 if both parents are affected.
The Simon Broome criteria are used for clinical diagnosis, which includes a total cholesterol level greater than 7.5 mmol/l and LDL-C greater than 4.9 mmol/l in adults or a total cholesterol level greater than 6.7 mmol/l and LDL-C greater than 4.0 mmol/l in children. Definite FH is diagnosed if there is tendon xanthoma in patients or first or second-degree relatives or DNA-based evidence of FH. Possible FH is diagnosed if there is a family history of myocardial infarction below age 50 years in second-degree relatives, below age 60 in first-degree relatives, or a family history of raised cholesterol levels.
Management of FH involves referral to a specialist lipid clinic and the use of high-dose statins as first-line treatment. CVD risk estimation using standard tables is not appropriate in FH as they do not accurately reflect the risk of CVD. First-degree relatives have a 50% chance of having the disorder and should be offered screening, including children who should be screened by the age of 10 years if there is one affected parent. Statins should be discontinued in women 3 months before conception due to the risk of congenital defects.
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This question is part of the following fields:
- Renal System
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Question 16
Incorrect
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A 39-year-old male visits his GP for a routine check-up of his high blood pressure. Despite being on a maximum dose of ramipril, amlodipine, and spironolactone, his blood pressure remains consistently at or above 160/100 mmHg. During the consultation, the patient reveals that he has been experiencing episodes of intense anxiety, sweating, palpitations, and fear about twice a week for the past six months.
What is the source of the hormone responsible for the symptoms experienced by this man?Your Answer: Zona glomerulosa of adrenal cortex
Correct Answer: Adrenal medulla
Explanation:The patient’s symptoms suggest a phaeochromocytoma, which is caused by a tumor in the adrenal medulla that leads to the release of excess epinephrine. This results in refractory hypertension and severe episodes of sweating, palpitations, and anxiety.
While the pituitary gland produces hormones like thyroid-stimulating hormone and adrenocorticotropic hormone, these hormones do not directly cause the symptoms seen in this patient. Additionally, excess ACTH production is associated with Cushing’s syndrome, which does not fit the clinical picture.
The adrenal cortex has three distinct zones, each responsible for producing different hormones. The zona fasciculata produces glucocorticoids like cortisol, which can lead to Cushing’s syndrome. The zona glomerulosa produces mineralocorticoids like aldosterone, which can cause uncontrolled hypertension and electrolyte imbalances. The zona reticularis produces androgens like testosterone. However, none of these conditions match the symptoms seen in this patient.
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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Question 17
Correct
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A 58-year-old man is diagnosed with benign prostatic hyperplasia and is prescribed finasteride. He is informed that the drug works by inhibiting the conversion of testosterone to dihydrotestosterone, thereby preventing further enlargement of the prostate. What is the mechanism of action of finasteride?
Your Answer: 5-alpha reductase inhibitor
Explanation:The enzyme 5-alpha-reductase is responsible for converting testosterone into dihydrotestosterone (DHT) in the testes and prostate. DHT is a more active form of testosterone. Finasteride is a medication that inhibits 5-alpha-reductase, preventing the conversion of testosterone to DHT. This can help prevent further growth of the prostate and is why finasteride is used clinically.
Alpha-1 agonist is an incorrect answer as it refers to adrenergic receptors and does not affect the conversion of testosterone to DHT. These drugs are used for benign prostate hyperplasia to relax smooth muscles in the bladder, reducing urinary symptoms. Tamsulosin is an example of an alpha-1 agonist.
Androgen antagonist is also incorrect as these drugs block the action of testosterone and DHT by preventing their attachment to receptors. They do not affect the conversion of testosterone to DHT.
Gonadotrophin-releasing hormone modulators are also an incorrect answer. These drugs affect the hypothalamus and the production of gonadotrophs, such as luteinizing hormone. They do not affect the conversion of testosterone to DHT.
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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Question 18
Correct
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A 3-year-old toddler is brought to the paediatric department due to stunted growth. During the medical history-taking, it is revealed that the parents are first cousins. Genetic testing confirms the diagnosis of Fanconi syndrome, which is known to cause renal dysfunction and electrolyte imbalances. The child's blood test results are as follows:
- Calcium: 2.4 mmol/L (normal range: 2.1-2.6)
- Phosphate: 0.3 mmol/L (normal range: 0.8-1.4)
- Magnesium: 0.9 mmol/L (normal range: 0.7-1.0)
Which part of the nephron is likely affected in this case, leading to the electrolyte disturbance observed in the patient?Your Answer: Proximal convoluted tubule
Explanation:The proximal convoluted tubule is where the majority of renal phosphate reabsorption occurs. This is relevant to a patient with hypophosphataemia, as dysfunction of the proximal convoluted tubule can lead to this condition. In addition to phosphate, the proximal convoluted tubule also reabsorbs glucose, amino acids, bicarbonate, sodium, and potassium.
The collecting duct, distal convoluted tubule, and glomerulus are not involved in the reabsorption of phosphate. The collecting duct regulates water reabsorption, the distal convoluted tubule plays a role in acid-base balance, and the glomerulus performs ultrafiltration. Thiazides and aldosterone antagonists act on the distal 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 19
Correct
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A 65-year-old male is referred to the cardiology department by his physician due to chest pain during physical activity. The cardiologist plans to evaluate for coronary artery blockage and prescribes a coronary CT angiography. The radiologist will administer a contrast dye intravenously during the imaging. What is the most crucial blood test to conduct before giving the contrast agent?
Your Answer: Urea and electrolytes
Explanation:Before administering contrast medium, it is important to assess renal function by checking the patient’s urea and electrolytes (U&Es) due to the nephrotoxic nature of the contrast medium.
Although cardiac enzymes can be useful in ruling out myocardial infarction, they are not relevant to the administration of contrast medium in this particular clinical scenario where an acute myocardial infarction is not suspected.
While a full blood count may be part of the patient’s regular workup, it is not necessary for assessing the administration of contrast medium.
Liver function does not need to be checked prior to administering contrast medium as it is not known to be hepatotoxic.
Although contrast medium can affect thyroid function in some patients due to its iodine content, it is not routinely checked before administration.
Contrast media nephrotoxicity is characterized by a 25% increase in creatinine levels within three days of receiving intravascular contrast media. This condition typically occurs between two to five days after administration and is more likely to affect patients with pre-existing renal impairment, dehydration, cardiac failure, or those taking nephrotoxic drugs like NSAIDs. Procedures that may cause contrast-induced nephropathy include CT scans with contrast and coronary angiography or percutaneous coronary intervention (PCI). Around 5% of patients who undergo PCI experience a temporary increase in plasma creatinine levels of more than 88 µmol/L.
To prevent contrast-induced nephropathy, intravenous 0.9% sodium chloride should be administered at a rate of 1 mL/kg/hour for 12 hours before and after the procedure. Isotonic sodium bicarbonate may also be used. While N-acetylcysteine was previously used, recent evidence suggests it is not effective. Patients at high risk for contrast-induced nephropathy should have metformin withheld for at least 48 hours and until their renal function returns to normal to avoid the risk of lactic acidosis.
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This question is part of the following fields:
- Renal System
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Question 20
Incorrect
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A 30-year-old female visits her GP complaining of ankle swelling. During the examination, her blood pressure is found to be 180/110 mmHg and a urine dipstick reveals protein +++ levels. She is referred to a nephrologist who performs a renal biopsy. The biopsy results show basement membrane thickening on light microscopy and subepithelial spikes on silver staining. Immunohistochemistry confirms the presence of PLA2. What is the probable diagnosis?
Your Answer: Type 2 membranoproliferative glomerulonephritis
Correct Answer: Membranous glomerulonephritis
Explanation:Membranous glomerulonephritis is the most common type of glomerulonephritis in adults and is the third leading cause of end-stage renal failure. It typically presents with proteinuria or nephrotic syndrome. A renal biopsy will show a thickened basement membrane with subepithelial electron dense deposits, creating a spike and dome appearance. The condition can be caused by various factors, including infections, malignancy, drugs, autoimmune diseases, and idiopathic reasons.
Management of membranous glomerulonephritis involves the use of ACE inhibitors or ARBs to reduce proteinuria and improve prognosis. Immunosuppression may be necessary for patients with severe or progressive disease, but many patients spontaneously improve. Corticosteroids alone are not effective, and a combination of corticosteroid and another agent such as cyclophosphamide is often used. Anticoagulation may be considered for high-risk patients.
The prognosis for membranous glomerulonephritis follows the rule of thirds: one-third of patients experience spontaneous remission, one-third remain proteinuric, and one-third develop end-stage renal failure. Good prognostic factors include female sex, young age at presentation, and asymptomatic proteinuria of a modest degree at the time of diagnosis.
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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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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 22
Incorrect
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A 24-year-old male patient visits his GP after observing swelling in his legs. He mentions that his urine has turned frothy. Upon conducting blood tests, the doctor discovers elevated cholesterol levels and reduced albumin.
What type of electrolyte imbalances should the GP anticipate in this individual?Your Answer: Hypovolaemic hypernatraemia
Correct Answer: Hypervolaemic hyponatraemia
Explanation:Hypervolaemic hyponatraemia can be caused by nephrotic syndrome.
Nephrotic syndrome is characterized by oedema, proteinuria, hypercholesterolaemia, and hypoalbuminaemia. It results in fluid retention, which can lead to hypervolaemic hyponatraemia. Urinary sodium levels would not show an increase if tested.
Understanding Hyponatraemia: Causes and Diagnosis
Hyponatraemia is a condition that can be caused by either an excess of water or a depletion of sodium in the body. However, it is important to note that there are also cases of pseudohyponatraemia, which can be caused by factors such as hyperlipidaemia or taking blood from a drip arm. To diagnose hyponatraemia, doctors often look at the levels of urinary sodium and osmolarity.
If the urinary sodium level is above 20 mmol/l, it may indicate sodium depletion due to renal loss or the use of diuretics such as thiazides or loop diuretics. Other possible causes include Addison’s disease or the diuretic stage of renal failure. On the other hand, if the patient is euvolaemic, it may be due to conditions such as SIADH (urine osmolality > 500 mmol/kg) or hypothyroidism.
If the urinary sodium level is below 20 mmol/l, it may indicate sodium depletion due to extrarenal loss caused by conditions such as diarrhoea, vomiting, sweating, burns, or adenoma of rectum. Alternatively, it may be due to water excess, which can cause the patient to be hypervolaemic and oedematous. This can be caused by conditions such as secondary hyperaldosteronism, nephrotic syndrome, IV dextrose, or psychogenic polydipsia.
In summary, hyponatraemia can be caused by a variety of factors, and it is important to diagnose the underlying cause in order to provide appropriate treatment. By looking at the levels of urinary sodium and osmolarity, doctors can determine the cause of hyponatraemia and provide the necessary interventions.
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This question is part of the following fields:
- Renal System
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Question 23
Incorrect
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A 65-year-old man with type 2 diabetes mellitus is undergoing his annual diabetic examination. He reports feeling more fatigued than usual and has missed his previous three annual check-ups. His blood glucose control has been inadequate, and he has not been adhering to his medications. His blood pressure measures 170/90 mmHg, and a urinalysis reveals microalbuminuria. A blood test shows that his glomerular filtration rate (GFR) is 27mL/min per 1.73m².
Assuming a renal biopsy is conducted on this patient, what are the anticipated findings?Your Answer: Crescent moon shaped glomeruli
Correct Answer: Nodular glomerulosclerosis and hyaline arteriosclerosis
Explanation:The patient in question is suffering from T2DM that is poorly controlled, resulting in diabetic nephropathy. The histological examination reveals the presence of Kimmelstiel-Wilson lesions (nodular glomerulosclerosis) and hyaline arteriosclerosis, which are caused by nonenzymatic glycosylation.
Amyloidosis is characterized by apple-green birefringence under polarised light.
Acute post-streptococcal glomerulonephritis is identified by enlarged and hypercellular glomeruli.
Rapidly progressive (crescentic) glomerulonephritis is characterized by crescent moon-shaped glomeruli.
Diffuse proliferative glomerulonephritis (often due to SLE) is identified by wire looping of capillaries in the glomeruli.
Understanding Diabetic Nephropathy: The Common Cause of End-Stage Renal Disease
Diabetic nephropathy is the leading cause of end-stage renal disease in the western world. It affects approximately 33% of patients with type 1 diabetes mellitus by the age of 40 years, and around 5-10% of patients with type 1 diabetes mellitus develop end-stage renal disease. The pathophysiology of diabetic nephropathy is not fully understood, but changes to the haemodynamics of the glomerulus, such as increased glomerular capillary pressure, and non-enzymatic glycosylation of the basement membrane are thought to play a key role. Histological changes include basement membrane thickening, capillary obliteration, mesangial widening, and the development of nodular hyaline areas in the glomeruli, known as Kimmelstiel-Wilson nodules.
There are both modifiable and non-modifiable risk factors for developing diabetic nephropathy. Modifiable risk factors include hypertension, hyperlipidaemia, smoking, poor glycaemic control, and raised dietary protein. On the other hand, non-modifiable risk factors include male sex, duration of diabetes, and genetic predisposition, such as ACE gene polymorphisms. Understanding these risk factors and the pathophysiology of diabetic nephropathy is crucial in the prevention and management of this condition.
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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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A 67-year-old man is undergoing a radical cystectomy due to T2 non-invasive bladder cancer. As a medical student shadowing the urological surgeons during the procedure, I was asked to identify the origin of the inferior and superior vesical arteries that needed to be ligated.
Your Answer: Renal artery
Correct Answer: Internal iliac artery
Explanation:The internal iliac artery is the correct answer as it supplies the pelvis, including the bladder, and gives rise to the superior and inferior vesical arteries.
The direct branch of the aorta is an incorrect answer as it refers to the origin of major vessels, not specifically related to the bladder.
The external iliac artery is also an incorrect answer as it continues into the leg and does not supply the bladder.
Similarly, the inferior mesenteric artery is an incorrect answer as it supplies the hind-gut of the digestive tract and is not directly related to the bladder.
Bladder Anatomy and Innervation
The bladder is a three-sided pyramid-shaped organ located in the pelvic cavity. Its apex points towards the symphysis pubis, while the base lies anterior to the rectum or vagina. The bladder’s inferior aspect is retroperitoneal, while the superior aspect is covered by peritoneum. The trigone, the least mobile part of the bladder, contains the ureteric orifices and internal urethral orifice. The bladder’s blood supply comes from the superior and inferior vesical arteries, while venous drainage occurs through the vesicoprostatic or vesicouterine venous plexus. Lymphatic drainage occurs mainly to the external iliac and internal iliac nodes, with the obturator nodes also playing a role. The bladder is innervated by parasympathetic nerve fibers from the pelvic splanchnic nerves and sympathetic nerve fibers from L1 and L2 via the hypogastric nerve plexuses. The parasympathetic fibers cause detrusor muscle contraction, while the sympathetic fibers innervate the trigone muscle. The external urethral sphincter is under conscious control, and voiding occurs when the rate of neuronal firing to the detrusor muscle increases.
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This question is part of the following fields:
- Renal System
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Question 25
Correct
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A 28-year-old female patient presents with haemoptysis and is diagnosed with metastatic tumour in the lung parenchyma. Upon biopsy, the histology reveals clear cells. What is the probable origin of the primary site?
Your Answer: Kidney
Explanation:Renal cell cancer includes a subtype known as clear cell tumours, which exhibit distinct genetic alterations located on chromosome 3.
Renal Lesions: Types, Features, and Treatments
Renal lesions refer to abnormal growths or masses that develop in the kidneys. There are different types of renal lesions, each with its own disease-specific features and treatment options. Renal cell carcinoma is the most common renal tumor, accounting for 85% of cases. It often presents with haematuria and may cause hypertension and polycythaemia as paraneoplastic features. Treatment usually involves radical or partial nephrectomy.
Nephroblastoma, also known as Wilms tumor, is a rare childhood tumor that accounts for 80% of all genitourinary malignancies in those under the age of 15 years. It often presents with a mass and hypertension. Diagnostic workup includes ultrasound and CT scanning, and treatment involves surgical resection combined with chemotherapy. Neuroblastoma is the most common extracranial tumor of childhood, with up to 80% occurring in those under 4 years of age. It is a tumor of neural crest origin and may be diagnosed using MIBG scanning. Treatment involves surgical resection, radiotherapy, and chemotherapy.
Transitional cell carcinoma accounts for 90% of lower urinary tract tumors but only 10% of renal tumors. It often presents with painless haematuria and may be caused by occupational exposure to industrial dyes and rubber chemicals. Diagnosis and staging are done with CT IVU, and treatment involves radical nephroureterectomy. Angiomyolipoma is a hamartoma type lesion that occurs sporadically in 80% of cases and in those with tuberous sclerosis in the remaining cases. It is composed of blood vessels, smooth muscle, and fat and may cause massive bleeding in 10% of cases. Surgical resection is required for lesions larger than 4 cm and causing symptoms.
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This question is part of the following fields:
- Renal System
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Question 26
Incorrect
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A 47-year-old man is under the care of an ophthalmologist for open angle glaucoma. He visits his GP to express his worries about the medication prescribed after reading online information. What is the medication that the ophthalmologist has prescribed, which can function as a diuretic by acting on the proximal convoluted tubule of the kidney?
Your Answer: Mannitol (osmotic diuretic)
Correct Answer: Acetazolamide (carbonic anhydrase inhibitor)
Explanation:Diuretic drugs are classified into three major categories based on the location where they inhibit sodium reabsorption. Loop diuretics act on the thick ascending loop of Henle, thiazide diuretics on the distal tubule and connecting segment, and potassium sparing diuretics on the aldosterone-sensitive principal cells in the cortical collecting tubule. Sodium is reabsorbed in the kidney through Na+/K+ ATPase pumps located on the basolateral membrane, which return reabsorbed sodium to the circulation and maintain low intracellular sodium levels. This ensures a constant concentration gradient.
The physiological effects of commonly used diuretics vary based on their site of action. furosemide, a loop diuretic, inhibits the Na+/K+/2Cl- carrier in the ascending limb of the loop of Henle and can result in up to 25% of filtered sodium being excreted. Thiazide diuretics, which act on the distal tubule and connecting segment, inhibit the Na+Cl- carrier and typically result in between 3 and 5% of filtered sodium being excreted. Finally, spironolactone, a potassium sparing diuretic, inhibits the Na+/K+ ATPase pump in the cortical collecting tubule and typically results in between 1 and 2% of filtered sodium being excreted.
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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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At which of the following locations is the highest amount of water absorbed?
Your Answer: Left colon
Correct Answer: Jejunum
Explanation:The small bowel, specifically the jejunum and ileum, is the primary location for water absorption in the gastrointestinal tract. While the colon does play a role in water absorption, its contribution is minor in comparison. However, if there is a significant removal of the small bowel, the importance of the colon in water absorption may become more significant.
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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This question is part of the following fields:
- Renal System
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Question 28
Correct
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A 67-year-old man with a history of heart failure visits the clinic complaining of breathlessness for the past four weeks. The breathlessness worsens with activity or when lying down, and he needs to sleep on three large pillows at night. He is currently taking ramipril, bisoprolol, furosemide, and bendroflumethiazide. You are contemplating adding a low dose of spironolactone to his current treatment. What accurately describes the mechanism of action of spironolactone?
Your Answer: Aldosterone antagonist
Explanation:Spironolactone is classified as an aldosterone antagonist, which is a type of potassium-sparing diuretic. It works by blocking the action of aldosterone on aldosterone receptors, which inhibits the Na+/K+ exchanger in the cortical collecting ducts. Amiloride is another potassium-sparing diuretic that inhibits the epithelial sodium channels in the cortical collecting ducts. Thiazide diuretics work by inhibiting the Na+ Cl- cotransporter in the distal convoluted tubule, while loop diuretics inhibit Na+ K+ 2Cl- cotransporters in the thick ascending loop of Henle. ACE inhibitors like ramipril, on the other hand, produce an antihypertensive effect by inhibiting ACE in the renin-angiotensin-aldosterone-system. In heart failure, diuretics are commonly used to reduce fluid overload and improve heart function. However, caution should be taken when using potassium-sparing diuretics like spironolactone in patients already at risk of hyperkalemia due to treatment with ACE inhibitors. Serum potassium levels should be monitored before and after starting spironolactone.
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 29
Incorrect
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A 47-year-old man is found to have a tumor in his right adrenal gland. The surgical plan is to remove it through an open anterior approach. What tool or technique will be most beneficial during the procedure?
Your Answer: Division of the ligament of Treitz
Correct Answer: Mobilisation of the colonic hepatic flexure
Explanation:In open adrenal surgery from an anterior approach, it is customary to perform mobilization of the hepatic flexure and right colon. However, mobilization of the liver is typically not necessary.
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 hepatorenal 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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This question is part of the following fields:
- Renal System
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Question 30
Correct
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You assess a 40-year-old woman who underwent a renal transplant 10 months ago for focal segmental glomerulosclerosis. She is currently taking a combination of tacrolimus, mycophenolate, and prednisolone. She complains of feeling unwell for the past five days with fatigue, jaundice, and joint pain. Upon examination, you note hepatomegaly, widespread lymphadenopathy, and jaundice. What is the probable diagnosis?
Your Answer: Epstein-Barr virus
Explanation:Complications that may arise after a transplant include CMV and EBV. CMV usually presents within the first 4 weeks to 6 months post transplant, while EBV can lead to post transplant lymphoproliferative disease, which typically occurs more than 6 months after the transplant. This disorder is often linked to high doses of immunosuppressant medication.
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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