Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 601: Which of the following statements regarding Goodpasture's syndrome is NOT true?

A. It is an autoimmune disease.
B. Antibodies are directed against the collagen type IV alpha3 chain of the glomerular basement membrane and pulmonary capillaries.
C. Patients may present with diffuse bilateral pulmonary infiltrates.
D. It typically causes slowly progressive renal failure. (Correct Answer)

Explanation: **Explanation:** Goodpasture’s Syndrome (Anti-GBM Disease) is a classic example of a **Type II Hypersensitivity reaction**. The hallmark of this condition is the presence of circulating autoantibodies directed against the **NC1 domain of the alpha-3 chain of Type IV collagen** [2]. This specific antigen is found in the basement membranes of both the renal glomeruli and the pulmonary alveoli. **Why Option D is the correct answer (False statement):** Goodpasture’s syndrome does not cause slowly progressive renal failure. Instead, it typically presents as **Rapidly Progressive Glomerulonephritis (RPGN)**. Without urgent intervention (plasmapheresis and immunosuppression), it can lead to end-stage renal disease within days to weeks [1]. On biopsy, it is characterized by **crescent formation** (Crescentic GN) and **linear IgG deposits** on immunofluorescence [1], [2]. **Analysis of other options:** * **Option A:** It is a prototypical organ-specific **autoimmune disease** triggered by environmental factors (like smoking or hydrocarbon exposure) in genetically susceptible individuals (HLA-DRB1*1501). * **Option B:** This accurately describes the pathophysiology. The **alpha-3 chain of Type IV collagen** is the specific target [2]. * **Option C:** Pulmonary involvement manifests as **alveolar hemorrhage**, which appears as diffuse bilateral pulmonary infiltrates on a chest X-ray. **High-Yield NEET-PG Pearls:** * **Triad:** Glomerulonephritis, Pulmonary hemorrhage, and Anti-GBM antibodies. * **Immunofluorescence:** Linear (not granular) deposition of IgG along the GBM [2]. * **Treatment:** The "Triple Therapy" includes **Plasmapheresis** (to remove antibodies), Corticosteroids, and Cyclophosphamide [1]. * **Strongest Risk Factor:** Strong association with **HLA-DR15 and DR4**.

Question 602: Hyaline casts are seen in which of the following conditions?

A. Acute tubular necrosis
B. Thrombotic microangiopathy
C. Normal urine (Correct Answer)
D. Pyelonephritis

Explanation: **Explanation:** **Hyaline casts** are the most common type of urinary cast. They are composed primarily of **Tamm-Horsfall mucoprotein** (uromodulin) secreted by the thick ascending limb of the Loop of Henle. Because they lack cellular inclusions, they appear transparent and colorless under light microscopy. 1. **Why "Normal urine" is correct:** Hyaline casts are not inherently pathological. They can be seen in healthy individuals, particularly following **strenuous exercise, dehydration**, or concentrated urine [1]. While they can increase in various renal diseases, their presence alone does not signify a specific pathology. 2. **Why the other options are incorrect:** * **Acute Tubular Necrosis (ATN):** Characterized by **"Muddy brown" granular casts** or renal tubular epithelial cell casts due to sloughing of necrotic cells. * **Thrombotic Microangiopathy (TMA):** Typically presents with hematuria and proteinuria; however, the hallmark is microangiopathic hemolytic anemia (schistocytes on smear). It does not produce specific diagnostic casts like hyaline casts. * **Pyelonephritis:** Characterized by **WBC (Leukocyte) casts**, which indicate tubulointerstitial inflammation or infection. **High-Yield Clinical Pearls for NEET-PG:** * **RBC Casts:** Pathognomonic for Glomerulonephritis (e.g., Post-streptococcal GN). * **WBC Casts:** Seen in Pyelonephritis and Acute Interstitial Nephritis (AIN). * **Fatty Casts ("Maltese Cross"):** Seen in Nephrotic Syndrome. * **Broad/Waxy Casts:** Indicative of Chronic Renal Failure (due to compensatory dilation of surviving nephrons). * **Granular Casts:** Often described as "weathered" cellular casts; seen in ATN (Muddy brown).

Question 603: Which of the following changes does NOT occur in malignant hypertension?

A. Petechial hemorrhages on cortical surface
B. Fibrinoid necrosis of arterioles
C. Intimal concentric thickening
D. Hyaline arteriosclerosis (Correct Answer)

Explanation: **Explanation:** Malignant hypertension (hypertensive emergency) is characterized by a sudden, severe rise in blood pressure (typically >200/120 mmHg), leading to acute vascular injury. The hallmark of this condition is **acute** hemodynamic stress, whereas **Hyaline arteriosclerosis** is a feature of **benign hypertension** or diabetes mellitus [1]. **1. Why Hyaline Arteriosclerosis is the Correct Answer:** Hyaline arteriosclerosis occurs due to chronic, long-standing "leakage" of plasma components across the vascular endothelium, resulting in pink, homogeneous thickening of the arteriolar walls [1]. It is a slow, degenerative process associated with chronic hypertension, not the acute, necrotizing injury seen in malignant hypertension. **2. Analysis of Other Options:** * **Fibrinoid necrosis (Option B):** This is the pathognomonic lesion of malignant hypertension. Acute pressure elevation causes necrosis of the vessel wall with accumulation of plasma proteins (fibrin), giving it a bright pink, granular appearance. * **Intimal concentric thickening (Option C):** Also known as **"Onion-skinning,"** this is a proliferative response to acute injury where smooth muscle cells migrate and proliferate in the intima, creating concentric layers. * **Petechial hemorrhages (Option D):** The rupture of necrotic arterioles and capillaries on the kidney's cortical surface leads to a "flea-bitten kidney" appearance, a classic gross finding in malignant hypertension. **NEET-PG High-Yield Pearls:** * **Flea-bitten Kidney:** Seen in Malignant Hypertension, Infective Endocarditis, and PSGN. * **Onion-skinning:** Characteristic of Hyperplastic Arteriolosclerosis (Malignant HTN). * **Hyaline Arteriosclerosis:** Associated with Benign HTN and Diabetic Microangiopathy [1]. * **Key Clinical Feature:** Malignant HTN must be accompanied by end-organ damage (e.g., papilledema, encephalopathy, or acute kidney injury).

Question 604: Which drug is not used to prevent contrast nephropathy?

A. Fenoldopam (Correct Answer)
B. N-acetylcysteine
C. Infusion of normal saline
D. Hemodialysis

Explanation: **Explanation:** Contrast-Induced Nephropathy (CIN) is a form of acute kidney injury occurring after the administration of iodinated contrast media. The primary pathophysiology involves renal vasoconstriction and direct tubular toxicity. **Why Fenoldopam is the correct answer:** Fenoldopam is a selective dopamine D1 receptor agonist that causes systemic and renal vasodilation. While theoretically beneficial for increasing renal blood flow, multiple clinical trials (including the CONTRAST study) have shown that **Fenoldopam does not reduce the risk of CIN**. In some cases, it may even cause hypotension, which can worsen renal perfusion. Therefore, it is not recommended for CIN prophylaxis. **Analysis of Incorrect Options:** * **N-acetylcysteine (NAC):** An antioxidant that scavenges free radicals and may cause vasodilation. While its efficacy is debated in recent trials (like PRESERVE), it is still frequently used in clinical practice and exams as a prophylactic agent. * **Infusion of Normal Saline:** This is the **most effective** and gold-standard preventive measure. Volume expansion dilutes the contrast media and prevents renal vasoconstriction. * **Hemodialysis:** While not a routine preventive measure for all patients, periprocedural hemodialysis or hemofiltration can be used in high-risk patients (e.g., those already on dialysis or with end-stage renal disease) to remove contrast media, though its routine use to *prevent* CIN in non-dialysis patients is generally not recommended. **High-Yield Clinical Pearls for NEET-PG:** * **Definition of CIN:** An increase in serum creatinine >0.5 mg/dL or >25% from baseline within 48–72 hours of contrast exposure. * **Best Preventive Strategy:** Isotonic saline (0.9% NaCl) at 1 mL/kg/hr for 12 hours before and after the procedure. * **Risk Factors:** Diabetes mellitus, pre-existing chronic kidney disease (CKD), dehydration, and high doses of ionic contrast. * **Other ineffective drugs:** Diuretics (like Furosemide), Mannitol, and Dopamine have all failed to show benefit and may actually increase the risk of CIN.

Question 605: Renal papillary necrosis is caused by?

A. Alcohol (Correct Answer)
B. Cocaine
C. Heroin
D. Morphine

Explanation: **Explanation:** Renal Papillary Necrosis (RPN) is a clinicopathologic entity characterized by ischemic necrosis of the renal papillae. The renal papillae are particularly vulnerable to ischemia because they are located at the distal end of the vasa recta, which has a naturally low oxygen tension. **Why Alcohol is the Correct Answer:** Chronic alcohol consumption is a recognized cause of renal papillary necrosis. The mechanism is multifactorial: alcohol acts as a potent diuretic leading to **dehydration**, which reduces medullary blood flow. Furthermore, alcohol metabolism generates oxidative stress and is often associated with the concurrent use of analgesics (to treat headaches/hangovers), which synergistically impairs prostaglandin-mediated vasodilation, leading to ischemic papillary infarction. **Analysis of Incorrect Options:** * **Cocaine:** While cocaine is highly nephrotoxic, it is most classically associated with **Rhabdomyolysis** leading to Acute Tubular Necrosis (ATN) or malignant hypertension and renal infarction, rather than isolated papillary necrosis. * **Heroin:** Heroin use is most famously linked to **Heroin-associated Nephropathy (HAN)**, which typically presents as Focal Segmental Glomerulosclerosis (FSGS). * **Morphine:** Morphine does not have a direct association with papillary necrosis. Its primary renal concern is the accumulation of metabolites (Morphine-6-glucuronide) in patients with pre-existing renal failure. **High-Yield Clinical Pearls for NEET-PG:** To remember the causes of Renal Papillary Necrosis, use the mnemonic **POSTCARDS**: * **P** - Pyelonephritis (Acute) * **O** - Obstruction of the urinary tract * **S** - **Sickle Cell Disease/Trait** (Most common cause in young patients) * **T** - Tuberculosis * **C** - Chronic Liver Disease/**Alcoholism** * **A** - **Analgesic Abuse** (NSAIDs inhibit PGE2, causing vasoconstriction of vasa recta) * **R** - Renal Transplant Rejection * **D** - **Diabetes Mellitus** (Most common overall cause) * **S** - Systemic Vasculitis

Question 606: What is the initial ECG change observed in Hyperkalemia?

A. Tall tented T waves (Correct Answer)
B. PR prolongation
C. Widening of the QRS complex
D. ST segment depression

Explanation: ### Explanation **Correct Option: A (Tall tented T waves)** Hyperkalemia increases the permeability of the cell membrane to potassium, leading to accelerated repolarization (Phase 3 of the action potential). This rapid repolarization manifests on the ECG as **tall, peaked, or "tented" T waves** [1]. This is the **earliest and most sensitive** ECG sign of hyperkalemia, typically occurring when serum potassium levels exceed 5.5–6.0 mEq/L [1]. These T waves are classically narrow-based and symmetrical, primarily seen in the precordial leads (V2–V4). **Analysis of Incorrect Options:** * **B. PR prolongation:** This occurs as potassium levels continue to rise (usually >6.5 mEq/L). High extracellular potassium causes partial depolarization of the resting membrane, leading to decreased excitability and slowed conduction through the AV node. * **C. Widening of the QRS complex:** This is a later sign (usually >7.0 mEq/L) indicating delayed intraventricular conduction [1]. If left untreated, the QRS eventually merges with the T wave to form a "sine wave" pattern, a precursor to ventricular fibrillation or asystole. * **D. ST segment depression:** While hyperkalemia can sometimes cause ST-segment changes (pseudoinfarction patterns), it is not the initial or characteristic change. ST depression is more commonly associated with hypokalemia or myocardial ischemia. **High-Yield Clinical Pearls for NEET-PG:** * **Sequence of Changes:** Tall T waves → PR prolongation/P wave flattening → QRS widening → Sine wave → Cardiac arrest [1]. * **Membrane Stabilization:** In patients with ECG changes, the immediate first step is **Intravenous Calcium Gluconate** (stabilizes the cardiac membrane) before shifting potassium into cells [2]. * **The "Rule of 5":** Potassium > 5.5 mEq/L is hyperkalemia; ECG changes often begin here. * **Pseudohyperkalemia:** Always rule out hemolysis during blood collection if ECG is normal despite high lab values.

Question 607: A patient has been passing stones recurrently in urine for the past few years. All of the following dietary restrictions are indicated EXCEPT:

A. Protein restriction
B. Calcium restriction (Correct Answer)
C. Salt restricted diet
D. Phosphate restriction

Explanation: The correct answer is **Calcium restriction**. [1] ### **Explanation** Historically, it was believed that reducing dietary calcium would decrease urinary calcium excretion and stone formation. However, modern nephrology (and high-yield NEET-PG concepts) dictates that **calcium restriction is actually contraindicated** in recurrent stone formers. When dietary calcium is restricted, there is less calcium available in the gut to bind to dietary **oxalate**. This leads to increased absorption of free oxalate, resulting in **hyperoxaluria**. Since oxalate is a much more potent promoter of calcium-oxalate stone formation than calcium itself, a low-calcium diet paradoxically increases the risk of stones. Patients are instead advised to maintain a **normal** dietary calcium intake (approx. 1000–1200 mg/day). [1] ### **Analysis of Other Options** * **Protein Restriction:** High animal protein intake increases the acid load, leading to hypercalciuria (via bone resorption) and hypocitraturia (citrate is a stone inhibitor). Restricting animal protein is a standard recommendation. * **Salt Restricted Diet:** High sodium intake inhibits the passive reabsorption of calcium in the proximal tubule, leading to hypercalciuria. Reducing salt intake is crucial to decrease urinary calcium levels. * **Phosphate Restriction:** While less common than salt/protein restriction, high phosphate intake can contribute to calcium-phosphate stone formation. In specific metabolic contexts, moderation is advised. ### **Clinical Pearls for NEET-PG** * **Fluid Intake:** The most important intervention is increasing fluid intake to maintain a urine output of >2.5 L/day. [1] * **Oxalate:** Patients should avoid high-oxalate foods (spinach, nuts, chocolate, tea). * **Citrate:** Citrate is a potent inhibitor of crystallization; hence, citrus fruits are beneficial. * **Thiazides:** If dietary changes fail, Thiazide diuretics are the drug of choice to reduce urinary calcium excretion.

Question 608: A 10-mm calculus in the right lower ureter associated with proximal hydroureteronephrosis is best treated with?

A. Extracorporeal shockwave lithotripsy
B. Antegrade percutaneous access
C. Open ureterolithotomy
D. Ureteroscopic retrieval (Correct Answer)

Explanation: The management of ureteral calculi depends on the size, location, and presence of complications. For a **10-mm calculus in the lower (distal) ureter**, **Ureteroscopic Lithotripsy (URSL) with retrieval** is the gold standard treatment [1]. 1. **Why Ureteroscopic Retrieval is correct:** The distal ureter is encased by the bony pelvis, which can shield stones from shockwaves in ESWL. Ureteroscopy allows direct visualization and fragmentation (usually via Holmium laser) of the stone. For stones >10 mm in the distal ureter, URSL has significantly higher stone-free rates compared to ESWL [1]. The presence of proximal hydroureteronephrosis indicates obstruction, necessitating prompt intervention to relieve pressure. 2. **Why other options are incorrect:** * **Extracorporeal Shockwave Lithotripsy (ESWL):** While non-invasive, ESWL is less effective for distal stones due to pelvic bone interference and has a higher rate of "Steinstrasse" (stone street) formation for stones ≥10 mm [1]. * **Antegrade Percutaneous Access:** This approach (PCNL) is typically reserved for large (>2 cm) renal stones or proximal ureteral stones where retrograde access fails. It is unnecessarily invasive for a lower ureteral stone. * **Open Ureterolithotomy:** This is now a "last-resort" procedure, reserved only for complex cases where endoscopic or laparoscopic methods have failed. **Clinical Pearls for NEET-PG:** * **Stone Size:** Stones <5 mm usually pass spontaneously with Medical Expulsive Therapy (MET) using Alpha-blockers (Tamsulosin). Around 90% of stones of less than 4 mm diameter pass spontaneously, but only 10% of stones bigger than 6 mm require intervention [1]. * **Location Rule:** For **Upper Ureter** stones <1 cm, ESWL is often preferred. For **Lower Ureter** stones or any ureteral stone >1 cm, URSL is superior [1]. * **Emergency:** If a stone is associated with fever/sepsis (infected hydronephrosis), the priority is **drainage** (DJ stenting or Percutaneous Nephrostomy), not definitive stone removal.

Question 609: A patient presents with urine that is red in color, has a positive dipstick for RBCs, and the supernatant is red while the sediment is clear. What is the most likely diagnosis?

A. Porphyria
B. Hematuria
C. Hemolysis
D. Rhabdomyolysis (Correct Answer)

Explanation: ### Explanation The correct answer is **Rhabdomyolysis**. The clinical scenario describes a classic presentation of **Myoglobinuria**. To differentiate causes of red urine, we must analyze the relationship between the urine dipstick and the physical appearance of the urine after centrifugation. 1. **The Underlying Concept:** * **Dipstick Positivity:** The urine dipstick uses the peroxidase activity of the heme molecule to detect blood [1]. It cannot distinguish between intact RBCs, free hemoglobin, or free myoglobin [1]. * **Centrifugation Test:** When urine is centrifuged, intact RBCs settle at the bottom (**red sediment, clear supernatant**) [1]. If the color remains in the **supernatant**, it indicates the presence of dissolved pigments (hemoglobin or myoglobin). * **Distinguishing Hemoglobin vs. Myoglobin:** In hemolysis (hemoglobinuria), the serum is usually pink/red because hemoglobin binds to haptoglobin and remains in circulation. In rhabdomyolysis (myoglobinuria), myoglobin is rapidly cleared from the blood, resulting in **red urine with clear/straw-colored plasma**. 2. **Analysis of Incorrect Options:** * **A. Porphyria:** Urine may turn "port-wine" red upon standing, but it is **dipstick negative** for blood as it contains porphyrins, not heme [1]. * **B. Hematuria:** Characterized by intact RBCs. Upon centrifugation, the RBCs form a **red sediment**, leaving a **clear supernatant** [1]. * **C. Hemolysis:** While this also results in a red supernatant and positive dipstick, it is typically associated with **red/pink serum** (hemoglobinemia), whereas the question points toward a classic presentation of myoglobinuria. ### High-Yield Clinical Pearls for NEET-PG: * **Triad of Rhabdomyolysis:** Muscle pain, weakness, and dark (tea-colored) urine. * **Most sensitive marker:** Serum Creatine Kinase (CK) levels (usually >5 times the upper limit). * **Electrolyte abnormalities:** Hyperkalemia, Hyperphosphatemia, and Hypocalcemia (early phase). * **Key Management:** Aggressive IV fluid resuscitation to prevent Acute Tubular Necrosis (ATN).

Question 610: Anion gap is increased in all except:

A. Ureterostomy (Correct Answer)
B. Ethylene glycol
C. Methylene glycol
D. Diabetic ketoacidosis

Explanation: ### Explanation Metabolic acidosis is categorized based on the **Anion Gap (AG)**, calculated as: $Na^+ - (Cl^- + HCO_3^-)$. The normal range is 8–12 mEq/L [1]. **1. Why Ureterostomy is the correct answer:** Ureterostomy (specifically ureterosigmoidostomy) causes a **Normal Anion Gap Metabolic Acidosis (NAGMA)**, also known as hyperchloremic metabolic acidosis [1]. When ureters are diverted into the bowel, the intestinal mucosa secretes bicarbonate ($HCO_3^-$) in exchange for chloride ($Cl^-$) from the urine. The loss of bicarbonate is balanced by a gain in chloride, keeping the anion gap within the normal range. **2. Why the other options are incorrect:** These conditions cause **High Anion Gap Metabolic Acidosis (HAGMA)** due to the accumulation of unmeasured organic acids: * **Ethylene glycol:** Metabolized into glycolic and oxalic acids. * **Methanol (Methylene glycol/Methanol):** Metabolized into formic acid [2]. (Note: "Methylene glycol" in the option likely refers to Methanol or a related toxic alcohol in the context of HAGMA). * **Diabetic Ketoacidosis (DKA):** Characterized by the production of acetoacetate and beta-hydroxybutyrate [3]. **Clinical Pearls for NEET-PG:** * **Mnemonic for HAGMA (MUDPILES):** **M**ethanol, **U**remia, **D**KA, **P**araldehyde, **I**ron/Isoniazid, **L**actic acidosis, **E**thylene glycol, **S**alicylates. * **Mnemonic for NAGMA (USED CARP):** **U**reterosigmoidostomy, **S**aline (Normal Saline infusion), **E**ndocrine (Addison’s), **D**iarrhea, **C**arbonic anhydrase inhibitors (Acetazolamide), **R**enal tubular acidosis (RTA), **P**ancreatic fistula. * **Gold Standard:** In toxic alcohol ingestion (Ethylene glycol/Methanol), both the **Anion Gap** and the **Osmolar Gap** are typically elevated.

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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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Nephrology — MCQs

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