Nephrology Practice Questions

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

Hypokalemia. **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].

Q: All are true about Renal tubular acidosis except?

Impaired acid production. 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).

Q: 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?

Metformin. **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.

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

Cardiovascular Disease. **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

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

Hypertension responds well to drugs. **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).

Q: Which of the following does not cause polyuria?

Rhabdomyolysis. **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].

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

Cranberry. ### 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].

Question 1

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

Accepted Answer

Hypokalemia

Answer

Chest pain

Answer

Acidosis

Answer

Hypertension

Question 2

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?

Accepted Answer

Administer hypotonic saline

Answer

Perform ultra-centrifugation

Answer

Initiate hemodialysis

Answer

Prescribe a high-protein diet

Question 3

All are true about Renal tubular acidosis except?

Accepted Answer

Impaired acid production

Answer

Impaired bicarbonate reabsorption

Answer

Inability to acidify urine

Answer

Nephrolithiasis

Question 4

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

Accepted Answer

Aminoglycoside toxicity

Answer

Contrast-induced nephrotoxicity

Answer

Hemolytic uremic syndrome

Answer

Glomerulonephritis

Question 5

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?

Accepted Answer

Metformin

Answer

Insulin

Answer

Metoprolol

Answer

Linagliptin

Question 6

Which of the following statements regarding microalbuminuria is not true?

Accepted Answer

Urine protein excretion between 30-299 mg/day is defined as microalbuminuria.

Answer

It cannot be detected by routine laboratory tests.

Answer

Microalbuminuria is an independent risk factor for cardiovascular risk in diabetic patients.

Answer

Microalbuminuria is the earliest marker of diabetic nephropathy.

Question 7

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

Accepted Answer

Cardiovascular Disease

Answer

Infection

Answer

Malignancy

Answer

Anemia

Question 8

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

Accepted Answer

Hypertension responds well to drugs

Answer

Kidneys may be asymmetrical

Answer

Atherosclerotic plaques are common

Answer

Serum creatinine may increase with ACE inhibitors

Question 9

Which of the following does not cause polyuria?

Accepted Answer

Rhabdomyolysis

Answer

Interstitial nephritis

Answer

Hypokalemia

Answer

Antidiuretic hormone insufficiency

Question 10

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

Accepted Answer

Cranberry

Answer

Grape

Answer

Raspberry

Answer

Orange

Nephrology — MCQs

Nephrology — MCQs

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