Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 511: Signs and symptoms of renal failure first appear when renal function deteriorates by more than:

A. 20%
B. 40%
C. 60% (Correct Answer)
D. 80%

Explanation: **Explanation:** The kidneys possess a remarkable functional reserve, meaning they can maintain homeostasis even after significant nephron loss. Clinical signs and symptoms of renal failure typically do not manifest until the **Glomerular Filtration Rate (GFR) falls below 40-50% of normal**. This corresponds to a functional deterioration of **more than 60%**. [1] 1. **Why 60% is correct:** In the stages of Chronic Kidney Disease (CKD), the initial loss of nephrons leads to compensatory hypertrophy of the remaining functional units [1]. It is only when approximately **60-75% of renal function is lost** (Stage 3 CKD) that patients begin to develop biochemical abnormalities (azotemia) and clinical symptoms like anemia, hypertension, and nocturia. 2. **Why other options are incorrect:** * **20% & 40%:** At these levels of deterioration, the patient is usually asymptomatic [1]. The remaining nephrons compensate effectively, and serum creatinine may still be within the normal range (the "creatinine-blind" area). * **80%:** By the time 80% of function is lost, the patient is in advanced renal failure (Stage 4). Symptoms are already well-established and severe. **High-Yield NEET-PG Pearls:** * **Renal Reserve:** The ability of the kidney to increase GFR in response to physiological stimuli (e.g., a high protein meal). This reserve is lost early in renal disease. * **Azotemia vs. Uremia:** Azotemia is the biochemical finding of elevated nitrogenous wastes; Uremia is the clinical syndrome resulting from advanced renal failure [1]. * **First Sign:** Often, the earliest clinical sign of decreasing renal function is **isosthenuria** (the inability to concentrate or dilute urine, fixed at a specific gravity of ~1.010). * **Creatinine Trend:** Serum creatinine does not rise significantly above the normal range until the GFR has decreased by at least 50%.

Question 512: Hyperkalemia without ECG changes may be treated with all of the following except?

A. Calcium gluconate (Correct Answer)
B. Salbutamol
C. Sodium bicarbonate
D. Insulin with dextrose

Explanation: ### Explanation The management of hyperkalemia is divided into three strategies: stabilizing the cardiac membrane, shifting potassium into cells, and removing potassium from the body [1]. **1. Why Calcium Gluconate is the Correct Answer:** Calcium gluconate (or calcium chloride) is used specifically to **stabilize the myocardial membrane** against the toxic effects of high potassium. It does not lower the serum potassium levels [1]. In clinical practice, calcium is indicated only when there are **ECG changes** (e.g., peaked T-waves, widened QRS) or severe hyperkalemia (>6.5 mEq/L). If a patient has hyperkalemia **without** ECG changes, calcium gluconate is not indicated as there is no immediate cardiac instability to counteract [1]. **2. Analysis of Incorrect Options (Potassium-Shifting Agents):** These agents are used to lower serum potassium levels by shifting it from the extracellular to the intracellular compartment [2]: * **Insulin with Dextrose:** The most reliable method to shift potassium into cells via the Na+/K+-ATPase pump. * **Salbutamol (Beta-2 Agonists):** Stimulates the Na+/K+-ATPase pump to promote intracellular potassium uptake. * **Sodium Bicarbonate:** Useful primarily in patients with concomitant metabolic acidosis; it shifts potassium into cells in exchange for hydrogen ions [2]. **3. NEET-PG High-Yield Pearls:** * **First-line for ECG changes:** Calcium gluconate (acts within 1–3 minutes; duration 30–60 mins) [1]. * **Most definitive treatment:** Hemodialysis (removes potassium from the body). * **Potassium removal agents:** Loop diuretics (Furosemide), Cation exchange resins (Patiromer, Sodium polystyrene sulfonate). * **"Pseudohyperkalemia":** Always rule this out (caused by hemolysis during blood draw or thrombocytosis) before aggressive treatment if the patient is asymptomatic with a normal ECG.

Question 513: Increased IgA deposits are seen in which condition?

A. Henoch Schonlein Purpura (Correct Answer)
B. Minimal Change Glomerulonephritis
C. Chronic Pyelonephritis
D. Hemolytic Uremic Syndrome

Explanation: ### Explanation **Correct Option: A. Henoch-Schönlein Purpura (HSP)** Henoch-Schönlein Purpura (now often called IgA Vasculitis) is a systemic small-vessel vasculitis characterized by the deposition of **IgA1-dominant immune complexes**. The renal manifestation of HSP is histologically indistinguishable from **IgA Nephropathy (Berger’s disease)**, showing prominent mesangial IgA deposits on immunofluorescence [1], [2]. The underlying pathophysiology involves "galactose-deficient IgA1," which triggers an immune response and subsequent deposition in the glomerular mesangium. **Why the other options are incorrect:** * **B. Minimal Change Glomerulonephritis (MCD):** This is characterized by the effacement of podocyte foot processes. Immunofluorescence is typically **negative** (pauci-immune) because it is not mediated by immune complex deposition [3]. * **C. Chronic Pyelonephritis:** This is a chronic tubulointerstitial inflammation resulting from recurrent infections or reflux. It is characterized by "thyroidization" of tubules and cortical scarring, not glomerular IgA deposition. * **D. Hemolytic Uremic Syndrome (HUS):** HUS is a **Thrombotic Microangiopathy (TMA)**. The pathology involves endothelial damage, fibrin thrombi in capillaries, and "double contouring" of the basement membrane. It does not involve IgA deposits. --- ### NEET-PG High-Yield Pearls * **The HSP Tetrad:** Palpable purpura (without thrombocytopenia), Arthralgia, Abdominal pain (colic/intussusception), and Renal involvement (Hematuria). * **IgA Nephropathy vs. HSP:** IgA Nephropathy is limited to the kidney (monorgan), whereas HSP is a systemic (multiorgan) version of the same disease spectrum. * **Most common site of IgA deposition:** Glomerular **mesangium** [1]. * **Synpharyngitic Hematuria:** Gross hematuria occurring *concurrently* (within 1-2 days) with an upper respiratory tract infection is a classic presentation of IgA-mediated renal disease [2].

Question 514: The finding of urine sodium concentration <20 mmol/L in hypovolemic hyponatremia implies:

A. Salt-wasting nephropathy
B. Diuretic therapy
C. Hypoaldosteronism
D. Trauma (Correct Answer)

Explanation: The core concept in evaluating hyponatremia is determining the **effective arterial blood volume (EABV)** and the kidney's response to it. [1], [2] **1. Why Trauma is correct:** In hypovolemic hyponatremia, the body has lost both water and sodium. If the loss is **extra-renal** (e.g., trauma with hemorrhage, burns, vomiting, or diarrhea), the kidneys function normally to compensate for the volume depletion. [2] The activation of the Renin-Angiotensin-Aldosterone System (RAAS) leads to maximal sodium reabsorption in the tubules to preserve volume. [3] Consequently, the **Urinary Sodium (UNa) drops to <20 mmol/L**. [2] In the context of trauma, blood loss or "third-spacing" triggers this intense renal sodium conservation. **2. Why other options are incorrect:** * **Salt-wasting nephropathy (A), Diuretic therapy (B), and Hypoaldosteronism (C):** These are all causes of **renal** sodium loss. [2] In these conditions, the defect lies within the kidney or the hormonal control of the kidney (lack of aldosterone). Despite being hypovolemic, the kidney cannot "hold onto" sodium, resulting in a **Urinary Sodium >20 mmol/L**. [2] **High-Yield Clinical Pearls for NEET-PG:** * **UNa <20 mmol/L:** Suggests extra-renal losses (GI loss, skin loss, third-spacing/trauma). [2] The kidneys are working correctly. * **UNa >20 mmol/L:** Suggests renal losses (Diuretics, ACE inhibitors, Mineralocorticoid deficiency, or intrinsic renal disease). [2] * **Fractional Excretion of Sodium (FeNa):** In oliguric states, FeNa <1% suggests pre-renal etiology (similar to UNa <20), while FeNa >2% suggests intrinsic renal damage (ATN). * **The "Rule of Thumb":** If the source of fluid loss is *not* the kidney, the UNa should be low. If the source of loss *is* the kidney, the UNa will be high. [2]

Question 515: In which of the following conditions is the formation of a calcium-containing kidney stone NOT likely?

A. Parathyroid adenoma.
B. Multiple myeloma.
C. Sarcoidosis.
D. Lesch-Nyhan syndrome. (Correct Answer)

Explanation: **Explanation:** The formation of kidney stones depends on the specific metabolic byproduct being excreted in excess. To answer this question, one must distinguish between disorders of **calcium metabolism** and **uric acid metabolism**. **1. Why Lesch-Nyhan Syndrome is the Correct Answer:** Lesch-Nyhan syndrome is an X-linked recessive disorder caused by a deficiency of the enzyme **Hypoxanthine-Guanine Phosphoribosyltransferase (HGPRT)**. This deficiency leads to the failure of the purine salvage pathway, resulting in the massive overproduction of **uric acid**. Consequently, patients develop **uric acid stones** (radiolucent), not calcium-containing stones [3]. Clinical hallmarks include self-mutilation, choreoathetosis, and gouty arthritis. **2. Why the Other Options are Incorrect:** * **A. Parathyroid Adenoma:** This is the most common cause of primary hyperparathyroidism [2]. It leads to hypercalcemia and significant **hypercalciuria**, which promotes the formation of calcium oxalate or calcium phosphate stones [1]. * **B. Multiple Myeloma:** This plasma cell dyscrasia causes extensive bone resorption via osteoclast-activating factors. The resulting **hypercalcemia** leads to hypercalciuria and the potential for calcium stone formation [2] (though nephrocalcinosis and "myeloma kidney" are also common). * **C. Sarcoidosis:** Granulomatous diseases like sarcoidosis involve macrophages that express **1-alpha-hydroxylase** [2]. This enzyme converts Vitamin D to its active form (1,25-dihydroxyvitamin D), increasing intestinal calcium absorption and leading to hypercalcemia/hypercalciuria and calcium stones. **Clinical Pearls for NEET-PG:** * **Most common kidney stone:** Calcium Oxalate (Radiopaque). * **Lesch-Nyhan Enzyme:** HGPRT (Mnemonic: **H**yperuricemia, **G**out, **P**issed off [self-mutilation], **R**etardation, **D**yserythropoiesis). * **Uric acid stones** are unique because they are **radiolucent** on X-ray but visible on CT scans [3]. * **Sarcoidosis** is a classic "high-yield" cause of hypercalcemia due to extra-renal Vitamin D activation [2].

Question 516: A 30-year-old male with NIDDM has a blood pressure of 150/90 mmHg and persistent albuminuria in traces on urine examination. What is the most appropriate line of treatment?

A. No treatment
B. Regular urine examination and monitoring of blood sugar
C. Administering lisinopril and restricting sodium intake (Correct Answer)
D. Restricting sodium intake only

Explanation: ### Explanation **1. Why Option C is Correct:** The patient presents with **Diabetic Nephropathy (DN)**, characterized by persistent albuminuria and hypertension (150/90 mmHg). In patients with diabetes and albuminuria, the standard of care is the initiation of an **ACE inhibitor (e.g., Lisinopril)** or an ARB [1]. * **Mechanism:** ACE inhibitors reduce intraglomerular pressure by causing vasodilation of the **efferent arteriole**. This slows the progression of renal damage and reduces proteinuria [1]. * **Sodium Restriction:** Reducing salt intake is essential as it enhances the antiproteinuric and antihypertensive effects of ACE inhibitors. **2. Why Other Options are Incorrect:** * **Option A & B:** These are passive approaches. Diabetic nephropathy is a progressive condition [2]; "watchful waiting" allows irreversible glomerular scarring (Kimmelstiel-Wilson lesions) to occur [2]. Early intervention is mandatory to prevent progression to End-Stage Renal Disease (ESRD) [1]. * **Option D:** While sodium restriction is beneficial, it is insufficient as a monotherapy. It does not address the hemodynamic changes (efferent vasoconstriction) driven by the Renin-Angiotensin-Aldosterone System (RAAS) in diabetic kidneys. **3. Clinical Pearls for NEET-PG:** * **Earliest Sign:** Microalbuminuria (30–300 mg/day) is the earliest clinical sign of DN [3]. * **Target BP:** For diabetic patients with proteinuria, the target BP is generally **<130/80 mmHg**. * **Drug of Choice:** ACE inhibitors/ARBs are the first-line agents regardless of baseline BP if albuminuria is present [1]. * **Screening:** Type 1 DM patients should be screened 5 years after diagnosis; Type 2 DM patients should be screened **at the time of diagnosis** [3]. * **Contraindication:** Never combine ACE inhibitors and ARBs due to the risk of hyperkalemia and acute kidney injury.

Question 517: Which of the following values are suggestive of acute tubular necrosis?

A. Urine osmolality > 500 mosmol/L H2O
B. Urine sodium > 40 meq/L (Correct Answer)
C. Blood urea nitrogen/plasma creatinine ratio > 20:1
D. Urine creatinine/plasma creatinine ratio > 40

Explanation: In Acute Tubular Necrosis (ATN), the primary pathology is structural damage to the tubular epithelial cells [1]. This leads to a loss of the kidney's ability to reabsorb sodium and concentrate urine [2]. **1. Why Option B is Correct:** In ATN, the damaged tubules cannot reabsorb sodium effectively. Consequently, a large amount of sodium is "wasted" into the urine, resulting in a **Urine Sodium > 40 mEq/L** and a Fractional Excretion of Sodium (FeNa) > 2%. **2. Why the other options are incorrect:** * **Option A (Urine Osmolality > 500):** This is characteristic of **Prerenal Azotemia**. In ATN, the tubules cannot concentrate urine, leading to dilute urine with an osmolality typically **< 350 mOsm/kg**. * **Option C (BUN/Creatinine Ratio > 20:1):** This ratio suggests **Prerenal Azotemia**, where slow flow in the nephron allows for excessive urea reabsorption [2]. In ATN, the ratio is usually normal or low (**< 10-15:1**) because urea is not being reabsorbed by the damaged tubules. * **Option D (Urine/Plasma Creatinine > 40):** High ratios indicate that the kidneys are successfully concentrating waste. In ATN, this ratio drops to **< 20** due to the failure of the concentrating mechanism. **High-Yield Clinical Pearls for NEET-PG:** * **Microscopy:** Look for **"Muddy Brown" granular casts** (pathognomonic for ATN). * **FeNa:** The most reliable differentiator. **FeNa < 1% = Prerenal**; **FeNa > 2% = ATN**. * **Exception:** FeNa can be < 1% in certain types of ATN, such as those induced by contrast dye or rhabdomyolysis (due to intense vasoconstriction).

Question 518: Autosomal dominant tubulointerstitial kidney disease (ADTKD) patients have a defect in which of the following genes?

A. MUC1 (Correct Answer)
B. PKD1
C. BBS 1
D. NPHS1

Explanation: **Explanation:** **Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD)** is a group of rare genetic disorders characterized by progressive interstitial fibrosis, tubular atrophy, and eventual end-stage renal disease (ESRD). Unlike Polycystic Kidney Disease, ADTKD typically presents with a **bland urinary sediment** (no blood or protein) and small-to-normal-sized kidneys on ultrasound. * **Why Option A is Correct:** The most common genetic cause of ADTKD is a mutation in the **MUC1 gene** (encoding Mucin-1), specifically a cytosine insertion in a repeat region. This leads to the production of a truncated, toxic protein (MUC1-fs) that accumulates in the tubular epithelial cells, causing cellular death and fibrosis. Other genes associated with ADTKD include **UMOD** (Uromodulin), **REN** (Renin), and **HNF1B**. * **Why Other Options are Incorrect:** * **B. PKD1:** Mutations in *PKD1* (85%) or *PKD2* cause **Autosomal Dominant Polycystic Kidney Disease (ADPKD)**, characterized by large, bilateral renal cysts and nephromegaly [1]. * **C. BBS 1:** Mutations in *BBS* genes cause **Bardet-Biedl Syndrome**, a ciliopathy characterized by obesity, polydactyly, retinitis pigmentosa, and renal anomalies. * **D. NPHS1:** Mutations in *NPHS1* (encoding Nephrin) cause **Congenital Nephrotic Syndrome of the Finnish type**, presenting with massive proteinuria in infancy. **High-Yield Clinical Pearls for NEET-PG:** * **Key Presentation:** Family history of ESRD + Normal urine microscopy + Hyperuricemia/Gout (especially in *UMOD* and *REN* mutations). * **Diagnosis:** Often requires genetic testing as renal biopsy shows non-specific interstitial fibrosis. * **Differentiating Feature:** Unlike ADPKD, kidneys in ADTKD are **not enlarged** and lack significant macro-cysts [1].

Question 519: Painless haematuria is found in all of the following conditions EXCEPT:

A. Cystitis (Correct Answer)
B. Renal carcinoma
C. Chronic glomerulonephritis
D. Polycystic kidney disease

Explanation: **Explanation:** The clinical distinction between painful and painless haematuria is a high-yield concept in NEET-PG nephrology. **Why Cystitis is the correct answer:** Cystitis (inflammation of the bladder, usually due to infection) is classically associated with **painful haematuria**. The inflammatory process irritates the bladder mucosa and trigone, leading to symptoms of dysuria, urgency, and suprapubic pain. In contrast, the question asks for conditions that present with *painless* haematuria. [1] **Analysis of Incorrect Options:** * **Renal Carcinoma (RCC):** Classically presents with "painless total haematuria." While the classic triad includes flank pain and a mass, the bleeding itself is typically painless unless clots cause ureteric colic. * **Chronic Glomerulonephritis:** Glomerular bleeding is typically painless [1]. It is often microscopic but can be macroscopic (smoky/cola-colored urine) without associated physical pain [2]. * **Polycystic Kidney Disease (ADPKD):** While cyst rupture can cause acute pain, ADPKD frequently presents with bouts of asymptomatic, painless gross haematuria due to the stretching of overlying vessels. **Clinical Pearls for NEET-PG:** 1. **Rule of Thumb:** Painless gross haematuria in an elderly patient is **Malignancy** (RCC or Bladder Cancer) until proven otherwise. 2. **Painful Haematuria Causes:** Think "Stones and Infections" (Urolithiasis, Cystitis, Urethritis) [1]. 3. **Glomerular vs. Post-Glomerular:** Look for dysmorphic RBCs or RBC casts to confirm a glomerular source (like GN), which is almost always painless [2]. 4. **IgA Nephropathy:** The most common cause of recurrent painless macroscopic haematuria synpharyngitically (coinciding with URTI).

Question 520: A patient on periodic renal dialysis requires minor oral surgery. When is the optimal timing for the procedure?

A. One day before dialysis
B. On the day of dialysis
C. One day after dialysis (Correct Answer)
D. One week after dialysis

Explanation: The optimal timing for minor oral surgery (or any elective minor procedure) in a patient on maintenance hemodialysis is **one day after the dialysis session**. This timing is chosen based on two critical physiological factors: 1. **Heparinization:** During hemodialysis, systemic heparin is administered to prevent clotting in the extracorporeal circuit [1]. The half-life of heparin is approximately 1.5 to 2 hours. By waiting 24 hours (one day after), the anticoagulant effect has completely worn off, significantly reducing the risk of post-operative hemorrhage. 2. **Physiological Optimization:** One day after dialysis, the patient is in their best possible metabolic state. Uremic toxins are at their lowest levels, electrolyte imbalances (like hyperkalemia) are corrected, and fluid volume is optimized [1]. This improves platelet function, which is often impaired in uremic states. **Analysis of Incorrect Options:** * **One day before dialysis:** This is the worst time for surgery. Uremic toxins and metabolic waste are at their peak, leading to maximum platelet dysfunction and an increased risk of cardiac arrhythmias due to electrolyte imbalances. * **On the day of dialysis:** If done before the session, the subsequent use of heparin during dialysis will cause excessive bleeding from the surgical site. If done after the session, the residual heparin effect still poses a bleeding risk. * **One week after dialysis:** This is not applicable for patients on "periodic" (usually thrice-weekly) dialysis. Waiting a week would lead to severe uremia and fluid overload [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Uremic Bleeding:** The primary defect is **platelet dysfunction** (impaired adhesion and aggregation), not a deficiency in clotting factors. * **Pre-op Management:** If a patient has a high bleeding risk, **Desmopressin (dDAVP)** can be used pre-operatively to acutely improve platelet function by increasing the release of von Willebrand factor. * **Antibiotic Prophylaxis:** While not mandatory for all, it should be considered if the patient has a prosthetic heart valve or if the dialysis access (AV fistula) is prone to infection.

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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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