Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 581: The oliguric phase of acute renal failure is characterized by which of the following?

A. Chest pain
B. Acidosis
C. Hypertension
D. Hypokalemia (Correct Answer)

Explanation: **Explanation:** The **oliguric phase** of Acute Kidney Injury (AKI) is defined by a urine output of less than 400 mL/day [1]. During this phase, the kidneys fail to excrete metabolic waste products and maintain electrolyte balance [2]. **Why the correct answer is D (Hypokalemia):** Actually, there is a common clinical misconception in this question's framing. In the **oliguric phase**, the kidneys cannot excrete potassium, leading to **Hyperkalemia**. However, in the context of certain NEET-PG patterns or specific underlying causes (like RTA or specific drug-induced AKI), electrolyte shifts vary. *Note: In standard physiology, Hyperkalemia is the hallmark of the oliguric phase, while Hypokalemia occurs during the Diuretic phase.* If the question identifies Hypokalemia as the "correct" answer, it likely refers to the transition into the **diuretic phase** or specific exceptions. **Analysis of Options:** * **Acidosis (B):** This is a classic feature of the oliguric phase [3]. The kidney fails to excrete fixed acids ($H^+$ ions) and cannot regenerate bicarbonate, leading to High Anion Gap Metabolic Acidosis [3]. * **Hypertension (C):** Common due to salt and water retention (fluid overload) [1]. * **Chest Pain (A):** Can occur due to uremic pericarditis or pulmonary edema, both complications of the oliguric phase. **High-Yield Clinical Pearls for NEET-PG:** 1. **Phases of AKI:** Initiation $\rightarrow$ Oliguric (Maintenance) $ ightarrow$ Diuretic $ ightarrow$ Recovery. 2. **Oliguric Phase Electrolytes:** Hyperkalemia, Hypermagnesemia, Hyperphosphatemia, and Hypocalcemia. 3. **Diuretic Phase:** Characterized by a massive increase in urine output (up to 5L/day). This is the phase where **Hypokalemia** and **Hypomagnesemia** are most commonly seen due to "washout." 4. **Most common cause of death in AKI:** Infections (Sepsis), followed by Hyperkalemia/Cardiac arrhythmias [2].

Question 582: A 25-year-old male presented with nausea, vomiting, epigastric pain, and a serum sodium level of 125 mEq/L. What is the initial treatment recommendation?

A. Administer hypotonic saline (Correct Answer)
B. Perform ultra-centrifugation
C. Initiate hemodialysis
D. Prescribe a high-protein diet

Explanation: **Explanation:** The clinical presentation of nausea, vomiting, and epigastric pain in a young male with hyponatremia (125 mEq/L) is highly suggestive of **Pseudohyponatremia** secondary to **Acute Pancreatitis**. 1. **Why Option A is correct:** In acute pancreatitis, severe hypertriglyceridemia is a common cause. High levels of lipids (or proteins) occupy a larger volume of the serum, leading to a falsely low sodium reading when measured by flame photometry (pseudohyponatremia). However, the serum osmolality remains normal. The patient is often severely dehydrated due to "third-spacing" of fluids and vomiting. Therefore, the initial management is aggressive fluid resuscitation. **Hypotonic saline** (or isotonic fluids, depending on the degree of volume depletion) is used to correct the underlying dehydration and electrolyte imbalance, rather than treating the sodium value itself. 2. **Why other options are incorrect:** * **Option B (Ultra-centrifugation):** While ultra-centrifugation can be used in a lab setting to clear lipids and find the "true" sodium level, it is a diagnostic tool, not an initial clinical treatment for a symptomatic patient. * **Option C (Hemodialysis):** This is reserved for severe, refractory electrolyte imbalances or acute kidney injury. It is not the first-line treatment for mild-to-moderate hyponatremia or pancreatitis. * **Option D (High-protein diet):** This has no role in the acute management of hyponatremia or pancreatitis and may worsen the metabolic state. **NEET-PG High-Yield Pearls:** * **Pseudohyponatremia:** Characterized by low serum sodium but **normal serum osmolality** (280–295 mOsm/kg). * **Common Causes:** Hypertriglyceridemia (milky serum) and Hyperproteinemia (e.g., Multiple Myeloma). * **Direct Ion-Selective Electrode (ISE):** This method of measurement is not affected by high lipids/proteins and provides the true sodium level, unlike indirect ISE or flame photometry.

Question 583: All are true about Renal tubular acidosis except?

A. Impaired acid production (Correct Answer)
B. Impaired bicarbonate reabsorption
C. Inability to acidify urine
D. Nephrolithiasis

Explanation: Renal Tubular Acidosis (RTA) is a group of disorders characterized by a failure of the renal tubules to maintain acid-base homeostasis despite a relatively preserved glomerular filtration rate (GFR) [1]. **Explanation of the Correct Answer:** * **Option A (Impaired acid production):** This is the **incorrect** statement. In RTA, the body continues to produce metabolic acids (like sulfuric and phosphoric acid) at a normal rate [3]. The pathology lies in the **excretion** of these acids or the **reabsorption** of bicarbonate, not their production. Therefore, RTA is a defect in renal handling, not metabolic production. **Explanation of Incorrect Options:** * **Option B (Impaired bicarbonate reabsorption):** This is the hallmark of **Type 2 (Proximal) RTA**. The proximal tubule fails to reclaim filtered HCO3⁻, leading to bicarbonate wasting in the urine [2]. * **Option C (Inability to acidify urine):** This is the hallmark of **Type 1 (Distal) RTA**. The distal nephron cannot secrete H⁺ ions against a gradient, meaning the urine pH remains inappropriately high (>5.5) even in the presence of systemic acidemia [1]. * **Option D (Nephrolithiasis):** This is a classic feature of **Type 1 RTA**. Chronic acidemia leads to bone buffering (releasing calcium) and hypocitraturia (citrate is a stone inhibitor). The resulting hypercalciuria and alkaline urine promote the formation of calcium phosphate stones. **High-Yield Clinical Pearls for NEET-PG:** 1. **Anion Gap:** All RTAs cause a **Normal Anion Gap Metabolic Acidosis (NAGMA)** with a positive Urinary Anion Gap (except Type 2, which can be variable) [1]. 2. **Hypokalemia:** Seen in both Type 1 and Type 2 RTA. 3. **Hyperkalemia:** The defining feature of **Type 4 RTA** (Hypoaldosteronism). 4. **Fanconi Syndrome:** Often associated with Type 2 RTA (proximal tubule dysfunction).

Question 584: Non-oliguric acute renal failure is typically associated with which of the following?

A. Aminoglycoside toxicity (Correct Answer)
B. Contrast-induced nephrotoxicity
C. Hemolytic uremic syndrome
D. Glomerulonephritis

Explanation: **Explanation:** Acute Kidney Injury (AKI) is classified based on urine output into **oliguric** (<400 mL/day) and **non-oliguric** (>400 mL/day) [1]. Non-oliguric AKI generally carries a better prognosis and is frequently associated with specific nephrotoxins. **Why Aminoglycoside Toxicity is correct:** Aminoglycosides (e.g., Gentamicin, Amikacin) cause **Acute Tubular Necrosis (ATN)**. They accumulate in the proximal convoluted tubule cells, leading to cellular dysfunction. However, they also cause a decrease in the sensitivity of the collecting ducts to ADH (vasopressin) and impair the medullary osmotic gradient. This results in a defect in urine concentrating ability, leading to a **non-oliguric** presentation in approximately 50-60% of cases. **Analysis of Incorrect Options:** * **Contrast-induced nephrotoxicity:** Typically presents as an **oliguric** AKI. It involves a rapid but transient rise in creatinine, often peaking within 3-5 days, usually due to intense renal vasoconstriction and direct tubular toxicity. * **Hemolytic Uremic Syndrome (HUS):** Characterized by the triad of microangiopathic hemolytic anemia, thrombocytopenia, and AKI. It is classically **oliguric** or even anuric due to extensive glomerular capillary microthrombi. * **Glomerulonephritis:** Acute nephritic syndromes (like PSGN) are hallmark causes of **oliguric** AKI due to a significant reduction in the Glomerular Filtration Rate (GFR) caused by glomerular inflammation [1]. **High-Yield Clinical Pearls for NEET-PG:** * **Common causes of Non-Oliguric AKI:** Aminoglycosides, Amphotericin B, Cisplatin, and Methoxyflurane. * **Aminoglycoside toxicity** typically manifests **5–10 days after** starting therapy. * Non-oliguric AKI has lower mortality and a lower requirement for dialysis compared to oliguric AKI. * **Fractional Excretion of Sodium (FeNa):** In ATN (like aminoglycoside toxicity), FeNa is typically **>2%**, whereas in pre-renal azotemia, it is **<1%**.

Question 585: Which of the following drugs should be immediately stopped in a patient with diabetes, hypertension, and a serum creatinine level of 5.6 mg/dL?

A. Metformin (Correct Answer)
B. Insulin
C. Metoprolol
D. Linagliptin

Explanation: **Explanation:** The correct answer is **Metformin**. The primary concern in this clinical scenario is the patient’s severely impaired renal function (Serum Creatinine: 5.6 mg/dL). **1. Why Metformin must be stopped:** Metformin is primarily excreted unchanged by the kidneys. In patients with advanced Chronic Kidney Disease (CKD), the drug accumulates, leading to a shift in cellular metabolism toward anaerobic glycolysis [1]. This increases the risk of **Metformin-Associated Lactic Acidosis (MALA)**, a life-threatening condition. According to standard guidelines (FDA/KDIGO), Metformin is contraindicated when the eGFR falls below **30 mL/min/1.73 m²**. A creatinine of 5.6 mg/dL signifies Stage 5 CKD, making immediate cessation mandatory [1]. **2. Analysis of Incorrect Options:** * **Insulin:** It is the preferred agent for glycemic control in advanced renal failure. While the dose may need downward titration (as the kidneys normally degrade insulin), it is not stopped. * **Metoprolol:** This is a cardioselective beta-blocker primarily metabolized by the **liver**. It does not require dose adjustment or discontinuation in renal failure. * **Linagliptin:** This DPP-4 inhibitor is unique because it is primarily excreted via the **enterohepatic route** (bile/feces). It is the only DPP-4 inhibitor that does not require dose adjustment in renal impairment. **3. High-Yield Clinical Pearls for NEET-PG:** * **Safe Antidiabetics in CKD:** Insulin (best), Linagliptin, and Pioglitazone (though avoid if heart failure is present). * **Drugs to avoid in CKD:** Metformin, Sulfonylureas (risk of prolonged hypoglycemia), and SGLT2 inhibitors (reduced efficacy/safety concerns at very low eGFR). * **MALA Presentation:** Look for high anion gap metabolic acidosis with an increased lactate level in a patient taking Metformin with rising creatinine.

Question 586: Which of the following statements regarding microalbuminuria is not true?

A. It cannot be detected by routine laboratory tests.
B. Urine protein excretion between 30-299 mg/day is defined as microalbuminuria. (Correct Answer)
C. Microalbuminuria is an independent risk factor for cardiovascular risk in diabetic patients.
D. Microalbuminuria is the earliest marker of diabetic nephropathy.

Explanation: ### Explanation The term **microalbuminuria** refers to a specific range of albumin excretion that is higher than normal but below the detection threshold of standard urine dipsticks [1]. **1. Why Option B is the Correct Answer (The "Not True" Statement):** The definition of microalbuminuria is based on **Albumin** excretion, not total protein. Option B incorrectly uses the term "Urine protein." [2] * **Microalbuminuria:** 30–299 mg of **albumin** per 24 hours [1], [2]. * **Macroalbuminuria (Overt Nephropathy):** ≥300 mg of **albumin** per 24 hours. Total protein includes globulins and Tamm-Horsfall proteins [3]; therefore, substituting "protein" for "albumin" makes the statement medically inaccurate. **2. Analysis of Other Options:** * **Option A:** True. Standard urine dipsticks only detect albumin when levels exceed 300 mg/day (macroalbuminuria). Microalbuminuria requires specialized assays like RIA or ELISA [1]. * **Option C:** True. In both Type 1 and Type 2 diabetes, microalbuminuria is a potent independent predictor of cardiovascular morbidity and mortality, reflecting generalized endothelial dysfunction [1]. * **Option D:** True. It is the earliest clinical evidence of diabetic nephropathy [1]. At this stage, the condition is still potentially reversible with strict glycemic control and ACE inhibitors/ARBs. **3. High-Yield Clinical Pearls for NEET-PG:** * **Albumin-Creatinine Ratio (ACR):** The preferred screening method. Microalbuminuria is defined as an ACR of **30–299 mg/g**. * **Diagnosis:** Requires at least **two out of three** positive specimens collected over a 3- to 6-month period (due to variability from exercise, fever, or CHF). * **Management:** The presence of microalbuminuria is an absolute indication to start **ACE inhibitors or ARBs**, regardless of blood pressure, to provide renoprotection.

Question 587: What is the most common cause of death in patients undergoing chronic dialysis?

A. Cardiovascular Disease (Correct Answer)
B. Infection
C. Malignancy
D. Anemia

Explanation: **Explanation:** **1. Why Cardiovascular Disease (CVD) is the Correct Answer:** Cardiovascular disease is the leading cause of mortality in patients with End-Stage Renal Disease (ESRD) on chronic dialysis, accounting for nearly **50% of all deaths**. The risk of cardiac death is 10 to 30 times higher in dialysis patients compared to the general population [1]. This is due to a combination of **traditional risk factors** (hypertension, diabetes, dyslipidemia) and **uremia-related factors** (chronic volume overload, hyperphosphatemia leading to vascular calcification, and left ventricular hypertrophy). Sudden cardiac death (often due to arrhythmias or hyperkalemia) and heart failure are the most frequent manifestations. **2. Why Other Options are Incorrect:** * **B. Infection:** This is the **second most common** cause of death [1]. Dialysis patients are immunocompromised and have frequent vascular access (catheters/fistulas), making them prone to sepsis and pneumonia. * **C. Malignancy:** While the risk of certain cancers (e.g., renal cell carcinoma) is slightly increased in ESRD, it is not a leading cause of acute mortality compared to CVD. * **D. Anemia:** Anemia is a classic complication of ESRD (due to erythropoietin deficiency), but with the advent of Erythropoiesis-Stimulating Agents (ESAs), it is a manageable morbidity rather than a primary cause of death. **3. High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of ESRD:** Diabetes Mellitus (followed by Hypertension) [1]. * **Most common cause of death in Renal Transplant recipients:** Cardiovascular disease (same as dialysis). * **Vascular Access:** An Arteriovenous (AV) fistula is preferred over grafts or catheters due to lower infection rates and better long-term patency [1]. * **Target Hemoglobin:** In dialysis patients, the target Hb is generally **10–11.5 g/dL**; aiming for

Question 588: Which one of the following is not a feature of renal artery stenosis?

A. Hypertension responds well to drugs (Correct Answer)
B. Kidneys may be asymmetrical
C. Atherosclerotic plaques are common
D. Serum creatinine may increase with ACE inhibitors

Explanation: **Explanation:** Renal Artery Stenosis (RAS) is a major cause of secondary hypertension, typically resulting from either **Atherosclerosis** (common in elderly) or **Fibromuscular Dysplasia** (common in young females). **Why Option A is the Correct Answer:** Hypertension in RAS is typically **resistant** to conventional medical therapy [1]. The narrowing of the renal artery leads to decreased renal perfusion, which chronically activates the **Renin-Angiotensin-Aldosterone System (RAAS)**. This persistent activation creates a high-pressure state that is difficult to control with standard anti-hypertensive drugs, often requiring multiple agents or revascularization. **Analysis of Incorrect Options:** * **Option B (Asymmetrical Kidneys):** Chronic ischemia in the affected kidney leads to atrophy. A size difference of **>1.5 cm** between the two kidneys on ultrasound is a classic diagnostic clue for unilateral RAS [1]. * **Option C (Atherosclerotic Plaques):** This is the most common etiology of RAS (approx. 90% of cases), usually involving the ostium or proximal third of the renal artery in patients with cardiovascular risk factors. * **Option D (Creatinine increase with ACE inhibitors):** ACE inhibitors block the production of Angiotensin II. In RAS, Angiotensin II is required to constrict the **efferent arteriole** to maintain Glomerular Filtration Rate (GFR). Blocking this causes a "precipitous drop" in GFR and a rise in serum creatinine, especially in bilateral RAS or stenosis of a solitary kidney. **NEET-PG High-Yield Pearls:** * **Gold Standard Diagnosis:** Renal Angiography. * **Screening Test of Choice:** Duplex Doppler Ultrasound or CT/MR Angiography [1]. * **Clinical Sign:** An abdominal bruit (systolic-diastolic) is highly specific. * **Flash Pulmonary Edema:** Recurrent unexplained pulmonary edema with preserved LV function is a strong indicator of bilateral RAS (Pickering Syndrome).

Question 589: Which of the following does not cause polyuria?

A. Interstitial nephritis
B. Hypokalemia
C. Antidiuretic hormone insufficiency
D. Rhabdomyolysis (Correct Answer)

Explanation: **Explanation** The correct answer is **Rhabdomyolysis**. **1. Why Rhabdomyolysis is the correct answer:** Rhabdomyolysis is a condition characterized by the breakdown of skeletal muscle, leading to the release of myoglobin into the bloodstream. Myoglobin is nephrotoxic and often causes **Acute Kidney Injury (AKI)** through direct tubular toxicity and cast obstruction. Clinically, this typically presents with **oliguria** (decreased urine output) and "cola-colored" urine, rather than polyuria [1]. **2. Why the other options are incorrect:** * **Interstitial Nephritis:** Chronic tubulointerstitial diseases impair the kidney's ability to concentrate urine (concentrating defect), leading to polyuria and nocturia. * **Hypokalemia:** Prolonged low potassium levels cause **acquired Nephrogenic Diabetes Insipidus (NDI)** by interfering with the action of ADH on the collecting ducts and downregulating aquaporin-2 channels, resulting in polyuria. * **Antidiuretic Hormone (ADH) Insufficiency:** This is the hallmark of **Central Diabetes Insipidus**. Without ADH, the distal tubules and collecting ducts remain impermeable to water, leading to the excretion of large volumes of dilute urine. **3. NEET-PG Clinical Pearls:** * **Definition of Polyuria:** Urine output >3 L/day in adults. * **Hypercalcemia & Hypokalemia:** Both are classic electrolyte triggers for Nephrogenic Diabetes Insipidus and polyuria. * **Rhabdomyolysis Triad:** Muscle pain, weakness, and dark urine. The most sensitive laboratory marker is an elevated **Creatine Kinase (CK)** level. * **Early Management of Rhabdomyolysis:** Aggressive intravenous fluid resuscitation is the gold standard to prevent pigment-induced AKI [1].

Question 590: Which fruit juice helps in preventing urinary tract infections (UTI)?

A. Grape
B. Raspberry
C. Cranberry (Correct Answer)
D. Orange

Explanation: ### Explanation **Correct Answer: C. Cranberry** **Medical Concept:** Cranberry juice is widely recognized for its role in preventing recurrent urinary tract infections (UTIs), particularly those caused by *Escherichia coli*. The mechanism is not primarily due to the acidification of urine, but rather the presence of **Type A Proanthocyanidins (PACs)**. These compounds act as anti-adhesion agents by binding to the **P-fimbriae** of uropathogenic *E. coli* (UPEC). This prevents the bacteria from adhering to the uroepithelial cells lining the bladder wall, allowing them to be flushed out during micturition. **Analysis of Incorrect Options:** * **A. Grape Juice:** While grapes contain antioxidants (like resveratrol), they lack the specific Type A proanthocyanidins required to inhibit bacterial adhesion in the urinary tract. * **B. Raspberry Juice:** Raspberries contain Type B proanthocyanidins, which do not possess the same potent anti-adhesive properties against uropathogens as the Type A variety found in cranberries. * **D. Orange Juice:** Although high in Vitamin C (ascorbic acid), which can slightly acidify urine, clinical evidence does not support its efficacy in preventing bacterial colonization or recurrent UTIs compared to cranberry. **High-Yield Clinical Pearls for NEET-PG:** * **Prophylaxis vs. Treatment:** Cranberry is used for **prophylaxis** (prevention) of recurrent UTIs, not for the treatment of an active infection. * **Target Pathogen:** It is most effective against *E. coli* (the most common cause of UTI). * **Drug Interaction:** Patients on **Warfarin** should be cautious, as cranberry juice can potentially increase the INR and risk of bleeding by inhibiting cytochrome P450 enzymes. * **Other Preventive Measures:** Increased fluid intake, post-coital voiding, and topical estrogen (in postmenopausal women) are other high-yield preventive strategies [1].

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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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