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Question 1
Incorrect
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A 56-year-old man presents to the outpatient cardiology clinic complaining of fatigue and weight gain. He has been diagnosed with type II diabetes for 14 years and has been taking metformin to control his blood sugar levels. An echocardiogram reveals a globally dilated left ventricle with a reduced ejection fraction of approximately 30%, and his NT-proBNP level is 1256 (<125 pg/mL). The healthcare provider decides to initiate empagliflozin therapy due to its cardioprotective effects in patients with heart failure with reduced ejection fraction. What is the primary mechanism of action for this new medication?
Your Answer: Ascending loop of Henle
Correct Answer: Proximal convoluted tubule
Explanation:Glucose reabsorption within the nephron is mainly concentrated in the proximal convoluted tubule.
The Loop of Henle and its Role in Renal Physiology
The Loop of Henle is a crucial component of the renal system, located in the juxtamedullary nephrons and running deep into the medulla. Approximately 60 litres of water containing 9000 mmol sodium enters the descending limb of the loop of Henle in 24 hours. The osmolarity of fluid changes and is greatest at the tip of the papilla. The thin ascending limb is impermeable to water, but highly permeable to sodium and chloride ions. This loss means that at the beginning of the thick ascending limb the fluid is hypo osmotic compared with adjacent interstitial fluid. In the thick ascending limb, the reabsorption of sodium and chloride ions occurs by both facilitated and passive diffusion pathways. The loops of Henle are co-located with vasa recta, which have similar solute compositions to the surrounding extracellular fluid, preventing the diffusion and subsequent removal of this hypertonic fluid. The energy-dependent reabsorption of sodium and chloride in the thick ascending limb helps to maintain this osmotic gradient. Overall, the Loop of Henle plays a crucial role in regulating the concentration of solutes in the renal system.
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This question is part of the following fields:
- Renal System
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Question 2
Incorrect
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A 67-year-old man is being evaluated on the ward. He was admitted with community-acquired pneumonia and required IV antibiotics. The results of his blood tests taken this morning are as follows:
- Sodium (Na+): 143 mmol/L (135 - 145)
- Potassium (K+): 6.5 mmol/L (3.5 - 5.0)
- Bicarbonate: 25 mmol/L (22 - 29)
- Urea: 5.5 mmol/L (2.0 - 7.0)
- Creatinine: 115 µmol/L (55 - 120)
An urgent ECG is ordered, which reveals peaked T waves and a loss of P waves.
What is the immediate course of action for this patient?Your Answer: Calcium resonium
Correct Answer: IV calcium gluconate
Explanation:The correct treatment for stabilizing the cardiac membrane in a patient with hyperkalaemia and ECG changes, such as peaked T waves and loss of P waves, is IV calcium gluconate. This is the first-line treatment option, as it can effectively stabilize the cardiac membrane and prevent arrhythmias. Other treatment options, such as calcium resonium, combined insulin/dextrose infusion, and nebulised salbutamol, can be used to treat hyperkalaemia, but only after IV calcium gluconate has been given.
Managing Hyperkalaemia: A Step-by-Step Guide
Hyperkalaemia is a serious condition that can lead to life-threatening arrhythmias if left untreated. To manage hyperkalaemia, it is important to address any underlying factors that may be contributing to the condition, such as acute kidney injury, and to stop any aggravating drugs, such as ACE inhibitors. Treatment can be categorised based on the severity of the hyperkalaemia, which is classified as mild, moderate, or severe based on the patient’s potassium levels.
ECG changes are also important in determining the appropriate management for hyperkalaemia. Peaked or ‘tall-tented’ T waves, loss of P waves, broad QRS complexes, and a sinusoidal wave pattern are all associated with hyperkalaemia and should be evaluated in all patients with new hyperkalaemia.
The principles of treatment modalities for hyperkalaemia include stabilising the cardiac membrane, shifting potassium from extracellular to intracellular fluid compartments, and removing potassium from the body. IV calcium gluconate is used to stabilise the myocardium, while insulin/dextrose infusion and nebulised salbutamol can be used to shift potassium from the extracellular to intracellular fluid compartments. Calcium resonium, loop diuretics, and dialysis can be used to remove potassium from the body.
In practical terms, all patients with severe hyperkalaemia or ECG changes should receive emergency treatment, including IV calcium gluconate to stabilise the myocardium and insulin/dextrose infusion to shift potassium from the extracellular to intracellular fluid compartments. Other treatments, such as nebulised salbutamol, may also be used to temporarily lower serum potassium levels. Further management may involve stopping exacerbating drugs, treating any underlying causes, and lowering total body potassium through the use of calcium resonium, loop diuretics, or dialysis.
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This question is part of the following fields:
- Renal System
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Question 3
Incorrect
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John, 72-years-old, visits his GP with concerns of frequent urination accompanied by a burning sensation and interrupted flow of urine that have persisted for approximately 5 months. During a digital rectal examination, his GP detects an enlarged prostate without nodules and his PSA levels are moderately elevated. The diagnosis is BPH. Which zone of the prostate experiences enlargement in BPH?
Your Answer: Central zone
Correct Answer: Transitional zone
Explanation:The periurethral gland area of the prostate gland does not have a distinct functional or histological identity. It is composed of cells from various regions of the prostate that are linked to different medical conditions. This part of the prostate does not typically experience enlargement and lacks glandular elements. Instead, it consists solely of fibrous tissue and smooth muscle cells, as its name implies.
Benign prostatic hyperplasia (BPH) is a common condition that affects older men, with around 50% of 50-year-old men showing evidence of BPH and 30% experiencing symptoms. The risk of BPH increases with age, with around 80% of 80-year-old men having evidence of the condition. Ethnicity also plays a role, with black men having a higher risk than white or Asian men. BPH typically presents with lower urinary tract symptoms (LUTS), which can be categorised into obstructive (voiding) symptoms and irritative (storage) symptoms. Complications of BPH can include urinary tract infections, retention, and obstructive uropathy.
Assessment of BPH may involve dipstick urine testing, U&Es, and PSA testing if obstructive symptoms are present or if the patient is concerned about prostate cancer. A urinary frequency-volume chart and the International Prostate Symptom Score (IPSS) can also be used to assess the severity of LUTS and their impact on quality of life. Management options for BPH include watchful waiting, alpha-1 antagonists, 5 alpha-reductase inhibitors, combination therapy, and surgery. Alpha-1 antagonists are considered first-line for moderate-to-severe voiding symptoms and can improve symptoms in around 70% of men, but may cause adverse effects such as dizziness and dry mouth. 5 alpha-reductase inhibitors may slow disease progression and reduce prostate volume, but can cause adverse effects such as erectile dysfunction and reduced libido. Combination therapy may be used for bothersome moderate-to-severe voiding symptoms and prostatic enlargement. Antimuscarinic drugs may be tried for persistent storage symptoms. Surgery, such as transurethral resection of the prostate (TURP), may also be an option.
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This question is part of the following fields:
- Renal System
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Question 4
Incorrect
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A 55-year-old man has recently been prescribed atorvastatin due to a high QRISK score and elevated cholesterol levels. He has a medical history of hypertension and takes amlodipine for it. However, he has returned to the GP after three weeks of taking atorvastatin, complaining of intolerable leg cramps. The GP is worried about the potential cardiac complications if the patient's cholesterol levels are not controlled. What alternative treatment options can be considered as second-line therapy?
Your Answer: Simvastatin
Correct Answer: Ezetimibe
Explanation:Ezetimibe is the recommended second line treatment for patients who cannot tolerate the side effects of statins, according to NICE guidelines. Atorvastatin is the preferred statin due to its lower incidence of side effects compared to simvastatin. Switching to simvastatin may not be beneficial and its dose would be limited to 20mg due to the concurrent use of amlodipine, which weakly inhibits the CYP enzyme responsible for simvastatin metabolism, effectively doubling the dose. Other options are not recommended by NICE as alternatives to statin therapy.
The Use of Ezetimibe in Treating Hypercholesterolaemia
Ezetimibe is a medication that helps lower cholesterol levels by inhibiting cholesterol receptors in the small intestine, reducing cholesterol absorption. In 2016, the National Institute for Health and Care Excellence (NICE) released guidelines on the use of ezetimibe in treating primary heterozygous-familial and non-familial hypercholesterolaemia.
For individuals who cannot tolerate or are unable to take statin therapy, ezetimibe monotherapy is recommended as an option for treating primary hypercholesterolaemia in adults. Additionally, for those who have already started statin therapy but are not seeing appropriate control of serum total or LDL cholesterol levels, ezetimibe can be coadministered with initial statin therapy. This is also recommended when a change from initial statin therapy to an alternative statin is being considered.
Overall, ezetimibe can be a useful medication in managing hypercholesterolaemia, particularly for those who cannot tolerate or do not see adequate results from statin therapy.
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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 56-year-old man with a history of alcohol excess and type 2 diabetes presents to the emergency department in an intoxicated state. He takes metformin and his recent HbA1c was 44 mmol/mol. On arrival, his blood sugar is 5.1 mmol/L and he frequently needs to urinate. The examination is unremarkable except for his intoxicated state. His blood test shows a creatinine level of 66 µmol/L (55 - 120). What is causing the patient's polyuria?
Your Answer:
Correct Answer: ADH suppression in the posterior pituitary gland
Explanation:Alcohol bingeing can result in the suppression of ADH in the posterior pituitary gland, leading to polyuria.
Polyuria, or excessive urination, can be caused by a variety of factors. A recent review in the BMJ categorizes these causes by their frequency of occurrence. The most common causes of polyuria include the use of diuretics, caffeine, and alcohol, as well as diabetes mellitus, lithium, and heart failure. Less common causes include hypercalcaemia and hyperthyroidism, while rare causes include chronic renal failure, primary polydipsia, and hypokalaemia. The least common cause of polyuria is diabetes insipidus, which occurs in less than 1 in 10,000 cases. It is important to note that while these frequencies may not align with exam questions, understanding the potential causes of polyuria can aid in diagnosis and treatment.
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This question is part of the following fields:
- Renal System
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Question 6
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:
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 7
Incorrect
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Which of the following is the primary location for the release of dehydroepiandrosterone in individuals?
Your Answer:
Correct Answer: Zona reticularis of the adrenal gland
Explanation:The adrenal cortex can be remembered with the mnemonic GFR-ACD, where DHEA is a hormone with androgenic effects that is primarily secreted by the adrenal gland.
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 8
Incorrect
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You are asked to evaluate a 53-year-old man who has developed sudden right arm pain while in the renal ward.
According to the patient, the pain started in his right arm within a few minutes while he was resting in bed. He denies any history of trauma. He was recently admitted due to significant edema throughout his body, including periorbital edema.
Upon examination, his right arm appears pale, cool to the touch, has a capillary refill time of 6 seconds, and no palpable radial pulse. However, his brachial pulse is present.
The patient is currently undergoing daily blood tests to monitor his renal function. On admission, his urine dipstick showed heavy proteinuria. A 24-hour urine collection was performed, and the results have just been reported:
Protein 6.2g/L
What is the probable cause of his right arm pain?Your Answer:
Correct Answer: Antithrombin III deficiency
Explanation:When a patient with nephrotic syndrome experiences symptoms such as those presented in this scenario, the possibility of a vascular event should be considered. The acute onset of symptoms and underlying renal disease suggest the need to differentiate between arterial and venous events, such as arterial thromboembolism or dissection and venous thromboembolism.
Nephrotic syndrome increases the risk of both venous and arterial thromboses due to the loss of coagulation factors and plasminogen, leading to a hypercoagulable state. In this case, the lack of a radial pulse and cool limb suggest arterial pathology, which is more strongly associated with the loss of antithrombin III than with renal loss of protein S.
Risk factors such as Factor V Leiden deficiency, the omission of low molecular weight heparin, and immobility in hospital are not specifically relevant to this case.
Possible Complications of Nephrotic Syndrome
Nephrotic syndrome is a condition that affects the kidneys, causing them to leak protein into the urine. This can lead to a number of complications, including an increased risk of thromboembolism, which is related to the loss of antithrombin III and plasminogen in the urine. This can result in deep vein thrombosis, pulmonary embolism, and renal vein thrombosis, which can cause a sudden deterioration in renal function.
Other complications of nephrotic syndrome include hyperlipidaemia, which can increase the risk of acute coronary syndrome, stroke, and other cardiovascular problems. Chronic kidney disease is also a possible complication, as is an increased risk of infection due to the loss of urinary immunoglobulin. Additionally, hypocalcaemia can occur due to the loss of vitamin D and binding protein in the urine.
It is important for individuals with nephrotic syndrome to be aware of these potential complications and to work closely with their healthcare providers to manage their condition and prevent further complications from occurring. Regular monitoring and treatment can help to minimize the risk of these complications and improve overall health outcomes.
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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 25-year-old suffers a groin stab wound resulting in hypovolaemic shock. What would be the probable observation on examining his urine?
Your Answer:
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.
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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 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:
Correct 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.
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This question is part of the following fields:
- Renal System
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