Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 781: Which of the following is a cause of hypokalemic metabolic alkalosis with hypertension?

A. Liddle syndrome (Correct Answer)
B. Bartter syndrome
C. Gitelman syndrome
D. Renal tubular acidosis

Explanation: ***Liddle syndrome*** - It is an **autosomal dominant** disorder characterized by a mutation in the **ENaC channel**, leading to increased sodium reabsorption and potassium excretion, thus causing **hypokalemia**, **metabolic alkalosis**, and **hypertension**. [1] - This condition mimics **primary hyperaldosteronism** but has **low plasma renin activity** and **low aldosterone levels**. [1] *Bartter syndrome* - This is a genetic disorder affecting the **Na-K-2Cl cotransporter** in the **thick ascending limb** of the loop of Henle, leading to **salt wasting** and compensatory **renin-angiotensin-aldosterone system activation**. - It presents with **hypokalemia**, **metabolic alkalosis**, but typically with **normal or low blood pressure**, not hypertension. *Gitelman syndrome* - This is an autosomal recessive disorder affecting the **thiazide-sensitive Na-Cl cotransporter** in the **distal convoluted tubule**. - It causes **hypokalemic metabolic alkalosis**, hypomagnesemia, and hypocalciuria, but patients are typically **normotensive** or **hypotensive**, distinguishing it from Liddle syndrome. *Renal tubular acidosis* - This is a group of disorders characterized by the **kidneys' inability to excrete acid** or **reabsorb bicarbonate**, leading to **metabolic acidosis**. [2] - While it can cause electrolyte abnormalities, hypokalemia is a feature of certain types (e.g., RTA type 1 and 2), but the defining feature is **metabolic acidosis**, not metabolic alkalosis, and it is not typically associated with hypertension from the primary tubular defect. [2]

Question 782: In Bartter syndrome defect is seen in:

A. Defect in proximal convoluted tubule (PCT)
B. Defect in distal convoluted tubule (DCT)
C. No defect
D. Defect in thick ascending limb of loop of Henle (Correct Answer)

Explanation: ***Defect in thick ascending limb of loop of Henle*** - Bartter syndrome results from a **genetic defect** affecting the activity of the **Na-K-2Cl cotransporter (NKCC2)** in the thick ascending limb of the loop of Henle. - This defect impairs **sodium, potassium, and chloride reabsorption**, leading to their increased excretion and characteristic electrolyte imbalances. *Defect in proximal convoluted tubule (PCT)* - Defects in the **proximal convoluted tubule** are typically associated with conditions like **Fanconi syndrome**, affecting reabsorption of glucose, amino acids, phosphate, and bicarbonate [1]. - This does not align with the characteristic **electrolyte imbalances** seen in Bartter syndrome, particularly hypokalemia and metabolic alkalosis. *Defect in distal convoluted tubule (DCT)* - Defects in the **distal convoluted tubule** are seen in conditions like **Gitelman syndrome**, which affects the Na-Cl cotransporter. - While both Bartter and Gitelman syndromes present with hypokalemia and metabolic alkalosis, the specific transporter affected and the severity of certain electrolyte disturbances differ. *No defect* - Bartter syndrome is a well-defined **genetic disorder** characterized by specific renal tubular defects. - Stating there is no defect is incorrect, as the syndrome arises directly from impaired renal tubule function.

Question 783: Which type of renal stones is associated with laxative abuse?

A. Uric acid stones (Correct Answer)
B. Struvite stones
C. Calcium oxalate stones
D. Ammonium urate stones

Explanation: ***Uric acid stones*** - Chronic laxative abuse can lead to **dehydration** and **diarrhea**, causing significant fluid and bicarbonate loss. This loss results in systemic metabolic acidosis and a persistently **acidic urine pH**. [1] - A persistently **acidic urine pH** (typically below 5.5) reduces the solubility of uric acid, promoting its crystallization and the formation of uric acid stones. [1] *Ammonium urate stones* - These stones are often seen in conditions with chronic **urinary tract infections** (UTIs) caused by **urea-splitting organisms** (e.g., Proteus), especially in children or in contexts of chronic diarrhea where ammonia production is increased. - While laxative abuse can cause diarrhea, it primarily leads to an acidic urine pH rather than the alkaline pH and high ammonia concentration typically associated with ammonium urate stones. *Struvite stones* - **Struvite stones** (magnesium ammonium phosphate) are predominantly associated with **urinary tract infections** by **urea-splitting organisms** (e.g., Proteus mirabilis) that elevate urinary pH and ammonia levels. [1] - Laxative abuse leads to an acidic urine pH, which is not conducive to struvite stone formation. *Calcium oxalate stones* - **Calcium oxalate stones** are the most common type of renal stone and are usually associated with hypercalciuria, hyperoxaluria, hypocitraturia, or low urine volume. - While dehydration from laxative abuse can increase urine concentration, the primary biochemical derangement leading to uric acid stones (acidic urine) is different from the risk factors for calcium oxalate stones.

Question 784: Which of the following types of kidney stones are commonly associated with urinary tract infections?

A. Struvite stones (Correct Answer)
B. Cystine stones
C. Xanthine stones
D. Calcium oxalate stones

Explanation: ***Struvite stones*** - **Struvite stones** (magnesium ammonium phosphate) are strongly associated with **urinary tract infections (UTIs)** caused by urease-producing bacteria like *Proteus* and *Klebsiella*. - These bacteria hydrolyze urea into ammonia and carbon dioxide, increasing urine pH and promoting the precipitation of struvite, often forming **staghorn calculi** [1]. *Cystine stones* - **Cystine stones** are caused by a **genetic defect** in amino acid transport, leading to increased excretion of cystine, ornithine, lysine, and arginine (COLA) in the urine. - They are not directly associated with UTIs but rather with a rare inherited metabolic disorder called **cystinuria**. *Xanthine stones* - **Xanthine stones** are very rare and typically occur in individuals with **xanthinuria**, a genetic disorder characterized by a deficiency in xanthine oxidase. - They are also not linked to UTIs but are a consequence of abnormal purine metabolism. *Calcium oxalate stones* - **Calcium oxalate stones** are the most common type of kidney stone, resulting from high levels of calcium and oxalate in the urine, often due to dietary factors, malabsorption, or idiopathic hypercalciuria. - While UTIs can complicate any kidney stone, **calcium oxalate stones** are not primarily *caused* by UTIs. [1]

Question 785: Muehrcke lines in nails are seen in

A. Bartter syndrome
B. Nail-patella syndrome
C. Acute tubular necrosis
D. Nephrotic syndrome (Correct Answer)

Explanation: ***Nephrotic syndrome*** - **Muehrcke lines** are paired, white, transverse lines that do not move with nail growth, characteristic of **hypoalbuminemia** seen in nephrotic syndrome [1]. - These lines are caused by **edema** in the nail bed, making them visible through the nail plate. *Bartter syndrome* - Characterized by a defect in the **sodium-potassium-chloride cotransporter** in the loop of Henle, leading to electrolyte imbalances. - It does not typically present with nail changes like Muehrcke lines. *Nail-patella syndrome* - A genetic disorder causing **skeletal abnormalities**, including hypoplastic or absent patellae and nail dysplasia. - Nail changes are usually structural abnormalities (e.g., triangular lunulae, ridging), not Muehrcke lines. *Acute tubular necrosis* - Involves damage to the **renal tubules**, often causing acute kidney injury and electrolyte disturbances. - While it can lead to kidney dysfunction, it is not specifically associated with Muehrcke lines.

Question 786: Most common acute complication of dialysis is

A. Hypotension (Correct Answer)
B. Bleeding
C. Dementia
D. Muscle cramps

Explanation: ***Hypotension*** - **Intradialytic hypotension** is the most common acute complication, occurring in 15-30% of dialysis sessions. - It is often caused by rapid removal of fluid (ultrafiltration), leading to a significant drop in blood pressure [1]. *Bleeding* - While bleeding can occur due to **anticoagulation** used during dialysis or as a complication of vascular access, it is less common than hypotension. - It is not considered the most frequent acute complication of the dialysis procedure itself. *Dementia* - **Dementia** is a chronic neurological condition that is not an acute complication directly attributable to a single dialysis session. - It can be a long-term comorbidity in patients with end-stage renal disease (ESRD), but not an immediate side effect. *Muscle cramps* - **Muscle cramps** are a relatively common acute complication during or immediately after dialysis, affecting about 5-20% of patients. - However, their frequency is generally lower than that of intradialytic hypotension [1].

Question 787: All are true about GFR except:

A. 30-40% decrease after 70 years of age
B. GFR is dependent on height in children
C. Chronic Kidney Disease (CKD) is defined as GFR < 60 ml/min/1.73 m² for 3 months or more.
D. Best estimated by creatinine clearance (Correct Answer)

Explanation: ***Best estimated by creatinine clearance*** - While **creatinine clearance** can be used as a measure of GFR, it is not the *best* estimate; it tends to slightly **overestimate** GFR due to tubular secretion of creatinine. [1] - The gold standard for measuring GFR involves methods like **inulin clearance**, but in clinical practice, GFR is often *estimated* using equations based on **serum creatinine** (e.g., CKD-EPI, MDRD). [2] *30-40% decrease after 70 years of age* - **Aging** is associated with a physiological decline in GFR, with a general decrease often cited as 30-40% after the age of 70 years. - This decline is part of the normal **age-related changes in renal function**. *GFR is dependent on height in children* - In children, GFR is often adjusted for **body surface area (BSA)**, which is calculated based on both **height and weight**, making height an important factor. [1] - This adjustment is crucial for accurate assessment of renal function in a growing pediatric population. *Chronic Kidney Disease (CKD) is defined as GFR < 60 ml/min/1.73 m² for 3 months or more.* - This statement accurately reflects the widely accepted definition of **Chronic Kidney Disease (CKD)** according to clinical guidelines. [3] - A GFR below this threshold sustained for more than three months indicates persistent kidney damage or dysfunction.

Question 788: Which disease does not recur in the kidney after a renal transplant?

A. Alport syndrome (Correct Answer)
B. Amyloidosis
C. Goodpasture's syndrome
D. Diabetic nephropathy (due to uncontrolled diabetes)

Explanation: **Alport syndrome** * **Alport syndrome** is a genetic disorder affecting type IV collagen, primarily in the kidney; recurrence is not observed in a renal allograft because the transplanted kidney provides new, healthy type IV collagen [2]. * The disease is due to a genetic defect in the recipient's collagen genes, so the transplanted kidney, which is genetically distinct, is not susceptible to the same primary disease process [2]. *Amyloidosis* * **Amyloidosis** can recur in the transplanted kidney, as it is a systemic disease where abnormal proteins continue to deposit in various organs, including the new kidney. * The underlying cause of amyloid production is typically not cured by a kidney transplant, making the new organ vulnerable to recurrence. *Goodpasture's syndrome* * **Goodpasture's syndrome** is an autoimmune disease where antibodies target type IV collagen in the glomerular basement membrane; these autoantibodies can attack the new kidney if they are still present at the time of transplant or re-emerge [1]. * Recurrence is a significant concern, although it can often be prevented by ensuring the patient is antibody-negative before transplantation and through immunosuppression [1]. *Diabetic nephropathy (due to uncontrolled diabetes)* * **Diabetic nephropathy** almost invariably recurs in the transplanted kidney if the recipient's diabetes remains uncontrolled after transplantation. * The metabolic environment, characterized by hyperglycemia, directly contributes to the damage of the new kidney, leading to the development of diabetic nephropathy over time.

Question 789: What condition is characterized by hypertension and hypokalemia?

A. Gitelman's Syndrome
B. Liddle's Syndrome (Correct Answer)
C. Bartter Syndrome
D. All of the options

Explanation: ***Liddle's Syndrome*** - This syndrome is characterized by **overactivity of the epithelial sodium channel (ENaC)** in the collecting ducts, leading to increased sodium reabsorption and potassium excretion. [1] - The resulting **sodium retention causes hypertension**, while the **potassium excretion leads to hypokalemia**. *Gitelman's Syndrome* - This is an **autosomal recessive kidney disorder** causing a defect in the **thiazide-sensitive NaCl cotransporter** in the distal convoluted tubule. - It presents with **hypokalemia and hypomagnesemia**, but typically with **normal or low blood pressure**, not hypertension. *Bartter Syndrome* - This is a group of **autosomal recessive salt-wasting tubulopathies** affecting the **Na-K-2Cl cotransporter** in the thick ascending limb of the loop of Henle. - It leads to **hypokalemia, metabolic alkalosis, and normal or low blood pressure**, similar to chronic loop diuretic use. *All of the options* - While all mentioned conditions involve **hypokalemia**, only **Liddle's Syndrome** is consistently associated with **hypertension**. - **Gitelman's and Bartter syndromes** typically present with **normal or low blood pressure**.

Question 790: Which of the following conditions is a direct indication for initiating dialysis?

A. Severe metabolic acidosis
B. Fluid overload
C. Severe hyperkalemia (Correct Answer)
D. Acute kidney injury

Explanation: ### Severe hyperkalemia - **Severe hyperkalemia** (potassium levels typically >6.5 mEq/L or rapidly rising, especially with ECG changes) is an immediate life-threatening indication for dialysis when conservative measures fail or are insufficient [1]. - Dialysis effectively removes **excess potassium** from the blood, preventing fatal cardiac arrhythmias. *Severe metabolic acidosis* - While **severe metabolic acidosis** (pH <7.1-7.2) can be an indication, it is often managed first with bicarbonate administration and is typically not a stand-alone **direct** *emergency* indication for dialysis unless accompanied by other severe features or resistance to medical therapy. - The decision to dialyze for acidosis often depends on the underlying cause, degree of renal failure, and response to initial management [2]. *Fluid overload* - **Fluid overload** is a common complication of kidney failure, but it becomes a *direct* indication for dialysis when it is **refractory to diuretic therapy** and causes life-threatening symptoms such as **pulmonary edema** [2]. - Without such refractory state and immediate danger, fluid overload itself is not always an *immediate* trigger for dialysis compared to severe hyperkalemia. *Acute kidney injury* - **Acute kidney injury** (AKI) is the underlying *condition* that can lead to indications for dialysis, but AKI itself is not a *direct indication* for dialysis. - Dialysis is initiated for the *complications* of AKI, such as refractory hyperkalemia, severe metabolic acidosis, or fluid overload, rather than the diagnosis of AKI alone [2].

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Acute Kidney Injury

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Chronic Kidney Disease

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Glomerular Diseases

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Tubulointerstitial Diseases

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Nephrotic and Nephritic Syndromes

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Urinary Tract Infections

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Renal Replacement Therapy

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Fluid and Electrolyte Disorders

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Acid-Base Disorders

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Kidney in Systemic Diseases

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Kidney Stones and Obstructive Uropathy

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Hypertension in Kidney Disease

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Nephrology — MCQs

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