Nephrology — MCQs

A 64-year-old man developed persistent back pain. On examination, his BP is 120/80, pulse 70, respiratory rate is 15, and temp is 98.6 deg F. Physical findings include severe pallor and evidence of muscle wasting. Urinalysis shows 4+ protein, and microscopy reveals occasional broad and occasional granular casts. Lab studies include: Serum creatinine = 5.1 mg/dl, serum Na = 141 mEq/L, K = 5.6 mEq/L, chloride = 101 mEq/L, CO2 = 14 mEq/L, serum calcium = 11.7 mg/dl, and serum phosphorus = 6.0 mg/dl. What is the most likely etiology?

Q206Easy

What is the most rapid method for lowering serum potassium levels?

Q207Medium

Which of the following drugs are implicated in the causation of nephrotic syndrome?

Q208Medium

A 78-year-old man with chronic kidney disease presents with generalized malaise. His past medical history includes heart failure, hypertension, and type 2 diabetes. Medications are ramipril, insulin, furosemide, and metoprolol. On physical examination, the blood pressure is 155/90 mm Hg, heart rate is 100/min, and respiration 24/min. The heart sounds are normal, there is no edema, and the lungs are clear on auscultation. An ECG is performed. What is the most likely diagnosis based on the ECG findings?

Q209Medium

Plasmapheresis is indicated in each of the following conditions except?

Q210Easy

Azotemia occurs when:

Nephrology Indian Medical PG Practice Questions and MCQs

Question 201: All of the following are associated with low complement levels, EXCEPT:

A. Lupus nephritis
B. Membranoproliferative glomerulonephritis
C. Atypical hemolytic uremic syndrome
D. Visceral sepsis associated glomerulonephritis (Correct Answer)

Explanation: The diagnosis of glomerulonephritis (GN) can be narrowed down by categorizing diseases based on serum complement levels (C3 and C4). **Why Option D is Correct:** **Visceral Sepsis-associated Glomerulonephritis** (often seen with deep-seated infections like staphylococcal endocarditis or osteomyelitis) typically presents with **normal complement levels**. Unlike Post-Streptococcal GN (PSGN), which is characterized by profound hypocomplementemia, sepsis-associated GN (particularly IgA-dominant varieties) does not usually consume systemic complement components to a degree that lowers serum levels. **Why Other Options are Incorrect:** * **Lupus Nephritis (Option A):** Classic example of the classical pathway activation, leading to **low C3 and low C4** [3]. * **Membranoproliferative Glomerulonephritis (MPGN) (Option B):** Type I involves the classical pathway (low C3/C4), while Type II (Dense Deposit Disease) involves the alternative pathway (low C3, normal C4) [1]. Both are "hypocomplementemic GNs." * **Atypical Hemolytic Uremic Syndrome (aHUS) (Option C):** Caused by dysregulation of the alternative complement pathway (e.g., Factor H mutations), leading to persistent complement consumption and **low C3 levels**. **NEET-PG High-Yield Pearls:** * **Low Complement GNs (The "Big 5"): 1. Post-Streptococcal GN (PSGN) [1] 2. Lupus Nephritis [3] 3. MPGN [1] 4. Cryoglobulinemic Vasculitis 5. Subacute Bacterial Endocarditis (SBE) associated GN (Note: *Visceral sepsis* is different from *SBE* in this context). * **Normal Complement GNs:** IgA Nephropathy [2], Henoch-Schönlein Purpura (HSP), ANCA-associated vasculitis [3], and Anti-GBM disease (Goodpasture’s) [3]. * **Timeframe:** In PSGN, C3 levels must return to normal within 6–8 weeks. If they remain low, suspect MPGN.

Question 202: Which of the following tests is most sensitive for detecting early diabetic nephropathy?

A. Serum Creatinine
B. Creatinine clearance
C. Microalbuminuria (Correct Answer)
D. Ultra sonography

Explanation: **Explanation:** **Microalbuminuria** (Option C) is the earliest clinical marker of diabetic nephropathy [1]. It refers to the excretion of small amounts of albumin (30–300 mg/day or an albumin-to-creatinine ratio of 30–300 mg/g) that are not detectable by standard urine dipstick tests [1]. In diabetes, chronic hyperglycemia leads to glomerular hyperfiltration and basement membrane thickening, causing this "leakage" [2]. Detecting it early is crucial because this stage is **potentially reversible** with strict glycemic control and ACE inhibitors/ARBs. **Why other options are incorrect:** * **Serum Creatinine (Option A):** This is a late marker. Creatinine levels often remain within the normal range until more than 50% of kidney function (GFR) is lost [3]. * **Creatinine Clearance (Option B):** While it measures GFR, it is not the most sensitive for *early* detection. In the very early stages of diabetes, GFR may actually be **increased** (hyperfiltration) rather than decreased. * **Ultrasonography (Option D):** USG is used to assess kidney size and rule out obstruction. In diabetic nephropathy, kidneys are typically **enlarged or normal-sized** even in advanced stages (unlike most chronic kidney diseases where kidneys shrink), but it cannot detect early functional damage. **High-Yield Clinical Pearls for NEET-PG:** * **Screening:** Type 1 DM patients should be screened 5 years after diagnosis; Type 2 DM patients should be screened **at the time of diagnosis** [2]. * **Gold Standard:** The most accurate method is a 24-hour urine collection, but the **Spot Urine Albumin-to-Creatinine Ratio (ACR)** is the preferred screening method due to convenience [3]. * **Progression:** Microalbuminuria (Stage III) → Macroalbuminuria/Overt Nephropathy (Stage IV) → ESRD (Stage V).

Question 203: What is the cause of hypercoagulation in nephrotic syndrome?

A. Loss of antithrombin III (AT III) (Correct Answer)
B. Decreased fibrinogen
C. Decreased metabolism of vitamin K
D. Increase in Protein C

Explanation: ### Explanation **Nephrotic syndrome** is characterized by a hypercoagulable state, leading to an increased risk of venous and arterial thromboembolism (most classically **Renal Vein Thrombosis**) [2]. **1. Why Option A is Correct:** The primary mechanism for hypercoagulability is the **urinary loss of low-molecular-weight proteins** due to increased glomerular permeability. **Antithrombin III (AT III)**, a natural anticoagulant that inhibits thrombin and Factor Xa, has a molecular weight similar to albumin. Its massive loss in the urine leads to a deficiency in the plasma, shifting the balance toward a pro-thrombotic state. **2. Why the Other Options are Incorrect:** * **Option B:** Fibrinogen levels are actually **increased**, not decreased [1]. The liver increases the synthesis of fibrinogen (and other clotting factors like V and VIII) as a compensatory response to low oncotic pressure. [1] * **Option C:** Vitamin K metabolism is not significantly altered in nephrotic syndrome. Hypercoagulability is driven by protein loss and hepatic overproduction, not vitamin K levels. * **Option D:** While Protein C and S levels can be variable, they are often **decreased** due to urinary loss. An increase in Protein C would be anticoagulant, which contradicts the hypercoagulable state. **Clinical Pearls for NEET-PG:** * **Most common complication:** Renal Vein Thrombosis (RVT), especially in **Membranous Nephropathy**. * **Triad of RVT:** Flank pain, hematuria, and a sudden increase in proteinuria/creatinine. * **Other factors:** Increased platelet aggregation and hyperlipidemia also contribute to the pro-thrombotic environment.

Question 204: Which is the most common electrolyte abnormality causing seizures in hospitalized patients?

A. Hyponatremia (Correct Answer)
B. Hypernatremia
C. Hypokalemia
D. Hyperkalemia

Explanation: **Explanation:** **Hyponatremia (Option A)** is the most common electrolyte abnormality encountered in clinical practice and the leading electrolyte-related cause of seizures in hospitalized patients. [1] The underlying mechanism involves **cerebral edema**. When serum sodium levels drop rapidly, the extracellular fluid becomes hypotonic relative to the intracellular fluid of brain cells. This osmotic gradient forces water into the neurons, causing them to swell. This increased intracranial pressure and neuronal dysfunction lower the seizure threshold, particularly when serum sodium falls below **120 mEq/L** or drops acutely. [1] **Why other options are incorrect:** * **Hypernatremia (Option B):** While it can cause CNS irritability, lethargy, and coma due to brain shrinkage (vascular rupture), it is statistically less common than hyponatremia as a cause of seizures in a hospital setting. * **Hypokalemia (Option C) & Hyperkalemia (Option D):** Potassium imbalances primarily affect **excitable cardiac and muscular tissues**. They are notorious for causing life-threatening arrhythmias and muscle weakness (paralysis) rather than primary central nervous system manifestations like seizures. **NEET-PG High-Yield Pearls:** * **Most common cause of SIADH:** Small cell carcinoma of the lung. * **Correction Rate:** To avoid **Osmotic Demyelination Syndrome (Central Pontine Myelinolysis)**, hyponatremia should not be corrected faster than **8–10 mEq/L in 24 hours**. [1] * **Drug-induced Hyponatremia:** SSRIs, Carbamazepine, and Thiazide diuretics are common culprits in hospitalized elderly patients. [1] * **Seizure Management:** In symptomatic hyponatremic seizures, **3% Hypertonic Saline** is the treatment of choice to acutely raise sodium levels by 4–6 mEq/L.

Question 205: A 64-year-old man developed persistent back pain. On examination, his BP is 120/80, pulse 70, respiratory rate is 15, and temp is 98.6 deg F. Physical findings include severe pallor and evidence of muscle wasting. Urinalysis shows 4+ protein, and microscopy reveals occasional broad and occasional granular casts. Lab studies include: Serum creatinine = 5.1 mg/dl, serum Na = 141 mEq/L, K = 5.6 mEq/L, chloride = 101 mEq/L, CO2 = 14 mEq/L, serum calcium = 11.7 mg/dl, and serum phosphorus = 6.0 mg/dl. What is the most likely etiology?

A. Renovascular disease
B. Thrombotic renal disease
C. Multiple myeloma (Correct Answer)
D. Systemic lupus erythematosus (SLE)

Explanation: ### Explanation The clinical presentation is classic for **Multiple Myeloma (MM)** leading to **Myeloma Kidney (Cast Nephropathy)**. **Why Multiple Myeloma is correct:** 1. **CRAB Features:** The patient exhibits **C**alcium elevation (11.7 mg/dl), **R**enal insufficiency (Cr 5.1 mg/dl), **A**nemia (severe pallor), and **B**one pain (persistent back pain) [1]. 2. **Protein Gap:** The urinalysis shows **4+ protein**, but in MM, this is typically due to **Bence-Jones proteins** (light chains). Standard dipsticks primarily detect albumin; however, high-grade proteinuria in an elderly patient with hypercalcemia and renal failure is a hallmark of MM [2]. 3. **Renal Findings:** The presence of **broad and granular casts** suggests chronic kidney disease (CKD) secondary to light-chain cast nephropathy, where light chains precipitate with Tamm-Horsfall protein in the distal tubules [1]. **Why other options are incorrect:** * **Renovascular disease:** Usually presents with refractory hypertension and a "flash" pulmonary edema clinical picture, not hypercalcemia or severe anemia. * **Thrombotic renal disease:** (e.g., HUS/TTP) would present with thrombocytopenia, schistocytes on smear, and often acute onset, not chronic back pain and hypercalcemia. * **Systemic Lupus Erythematosus (SLE):** Typically affects younger females. While it causes renal failure (Lupus Nephritis), it presents with "active" urinary sediment (RBC casts) and hypocalcemia (if in renal failure), not hypercalcemia. **NEET-PG High-Yield Pearls:** * **Hypercalcemia + Renal Failure + Anemia** in an elderly patient = Think Multiple Myeloma until proven otherwise. * **Bence-Jones Proteinuria:** These are monoclonal light chains. They are **not** detected by conventional dipsticks (which detect albumin) but are detected by the **Sulfosalicylic Acid (SSA) test** or urine electrophoresis [1]. * **Diagnosis:** Bone marrow biopsy (>10% plasma cells) and Serum Protein Electrophoresis (M-spike) [1]. * **Renal Pathology:** The most common cause of renal failure in MM is **Intratubular Cast Nephropathy** [2].

Question 206: What is the most rapid method for lowering serum potassium levels?

A. Albuterol
B. Insulin drip (Correct Answer)
C. Calcium gluconate
D. Sodium bicarbonate

Explanation: The management of hyperkalemia focuses on three goals: membrane stabilization, intracellular shifting, and elimination. **Why Insulin Drip is Correct:** Intravenous insulin (typically 10 units of regular insulin given with 25-50g of Dextrose) is the **most rapid and reliable method for shifting potassium** from the extracellular to the intracellular compartment [2]. It works by stimulating the **Na+/K+-ATPase pump** in skeletal muscle. The effect begins within **10–20 minutes**, peaks at 30–60 minutes, and can lower serum potassium by 0.5 to 1.5 mEq/L. Infusions of insulin and glucose are highly effective for the temporary relief of hyperkalemia [2]. **Analysis of Incorrect Options:** * **A. Albuterol:** This is a $\beta_2$-agonist that also shifts potassium intracellularly via the Na+/K+-ATPase pump. However, it takes slightly longer to act (approx. 30 mins) and often requires very high doses (20mg nebulized), making it less predictable than insulin. * **C. Calcium Gluconate:** This is the **fastest-acting** treatment for hyperkalemia (onset <5 mins), but it **does not lower serum potassium levels.** It antagonizes the membrane excitability to protect the heart from arrhythmias [1]. * **D. Sodium Bicarbonate:** It shifts potassium into cells by increasing pH, but its efficacy is slow and inconsistent unless the patient has underlying metabolic acidosis. **NEET-PG High-Yield Pearls:** * **First-line drug for ECG changes:** Calcium gluconate (stabilizes myocardium) [1]. * **Most definitive treatment:** Hemodialysis (removes potassium from the body). * **Common side effect of Insulin/Dextrose:** Hypoglycemia (monitor blood glucose for 4–6 hours). * **Potassium-lowering "Shift" agents:** Insulin, $\beta_2$-agonists, and Bicarbonate.

Question 207: Which of the following drugs are implicated in the causation of nephrotic syndrome?

A. Gold, Rifampicin, Ibuprofen (Correct Answer)
B. Rifampicin, Ibuprofen, Captopril
C. Amphotericin B, Rifampicin, Captopril
D. Gold, Amphotericin B, Rifampicin

Explanation: Explanation: Nephrotic syndrome is characterized by heavy proteinuria (>3.5g/day), hypoalbuminemia, and edema. Certain drugs can trigger this by causing glomerular injury, most commonly **Minimal Change Disease (MCD)** or **Membranous Nephropathy (MN)** [1]. **Why Option A is Correct:** * **Gold salts:** Historically used for Rheumatoid Arthritis, gold is a classic cause of **Membranous Nephropathy** due to subepithelial immune complex deposition. * **Rifampicin:** While primarily known for causing Acute Interstitial Nephritis (AIN), it is also a documented cause of **Minimal Change Disease**, leading to sudden-onset nephrotic syndrome. * **Ibuprofen (NSAIDs):** NSAIDs are high-yield triggers for both **Minimal Change Disease** and **Membranous Nephropathy** [1]. They can also cause a unique combination of AIN with nephrotic-range proteinuria. **Analysis of Incorrect Options:** * **Amphotericin B (Options C & D):** This is a potent nephrotoxin, but it causes **Type 1 Renal Tubular Acidosis (RTA)** and **Acute Tubular Necrosis (ATN)**, characterized by electrolyte wasting (hypokalemia, hypomagnesemia) rather than nephrotic syndrome. * **Captopril (Options B & C):** While ACE inhibitors like Captopril can rarely cause Membranous Nephropathy (especially at high doses), they are more clinically significant for causing **Acute Kidney Injury (AKI)** in patients with bilateral renal artery stenosis [1] or for their *protective* role in reducing proteinuria in diabetic nephropathy. **NEET-PG High-Yield Pearls:** * **Membranous Nephropathy triggers:** Gold, Penicillamine, NSAIDs, Captopril, and Mercury. * **Minimal Change Disease triggers:** NSAIDs, Rifampicin, Lithium, and Interferon-α [1]. * **Focal Segmental Glomerulosclerosis (FSGS) triggers:** Heroin, Pamidronate, and Sirolimus. * **Drug of choice for drug-induced MCD:** Discontinuation of the offending agent; steroids are used if recovery is delayed.

Question 208: A 78-year-old man with chronic kidney disease presents with generalized malaise. His past medical history includes heart failure, hypertension, and type 2 diabetes. Medications are ramipril, insulin, furosemide, and metoprolol. On physical examination, the blood pressure is 155/90 mm Hg, heart rate is 100/min, and respiration 24/min. The heart sounds are normal, there is no edema, and the lungs are clear on auscultation. An ECG is performed. What is the most likely diagnosis based on the ECG findings?

A. hyperkalemia (Correct Answer)
B. hypercalcemia
C. hypernatremia
D. pericarditis

Explanation: ***Hyperkalemia*** - **Peaked T waves**, **widened QRS complex**, and **flattened P waves** are classic ECG findings in hyperkalemia, fitting this patient's presentation. - **Chronic kidney disease** reduces potassium excretion, and **ramipril (ACE inhibitor)** blocks aldosterone-mediated potassium elimination, creating high risk for hyperkalemia. *Hypercalcemia* - ECG typically shows **shortened QT interval** due to accelerated ventricular repolarization, not the peaked T waves expected here. - Clinical features include **confusion**, **kidney stones**, and **bone pain**, which are not described in this case. *Hypernatremia* - Does **not produce specific ECG changes** that would explain the abnormal findings described in this scenario. - Primarily causes **neurological symptoms** like altered mental status and seizures rather than cardiac manifestations. *Pericarditis* - ECG findings include **saddle-shaped ST elevation** across multiple leads and **PR segment depression**, different from hyperkalemia changes. - Clinical presentation typically involves **chest pain** that worsens with inspiration and improves when leaning forward, not generalized malaise.

Question 209: Plasmapheresis is indicated in each of the following conditions except?

A. Hemolytic-uremic syndrome
B. Goodpasture's syndrome
C. Nephrotic syndrome (Correct Answer)
D. Guillain-Barre syndrome

Explanation: **Explanation:** The correct answer is **Nephrotic Syndrome (Option C)**. Plasmapheresis (Therapeutic Plasma Exchange) is a procedure used to remove high-molecular-weight substances, such as pathogenic autoantibodies, immune complexes, or toxins, from the plasma. **1. Why Nephrotic Syndrome is the Correct Answer:** Nephrotic syndrome is a clinical state characterized by heavy proteinuria, hypoalbuminemia, and edema [2]. It is primarily managed with corticosteroids, immunosuppressants (like Cyclophosphamide or Rituximab), and ACE inhibitors [1]. Plasmapheresis has no established role in the routine management of Nephrotic Syndrome, as the pathology involves a breach in the glomerular filtration barrier rather than a circulating toxin or antibody that requires rapid mechanical removal. **2. Analysis of Other Options:** * **Goodpasture’s Syndrome (Option B):** This is a **Category I indication** for plasmapheresis [3]. It involves anti-GBM antibodies attacking the lungs and kidneys. Rapid removal of these antibodies is life-saving and prevents irreversible renal failure [3]. * **Guillain-Barre Syndrome (Option D):** Plasmapheresis is a standard treatment (alongside IVIG) to remove demyelinating antibodies, significantly shortening the recovery time and reducing the need for mechanical ventilation. * **Hemolytic-Uremic Syndrome (Option A):** Specifically in **Atypical HUS** (complement-mediated) or HUS associated with TTP, plasmapheresis is used to remove mutant complement factors or provide ADAMTS13 protease [4]. **NEET-PG High-Yield Pearls:** * **Absolute Indications for Plasmapheresis:** TTP (Treatment of choice), Goodpasture’s [3], Myasthenia Gravis (crisis), and ANCA-associated Vasculitis with severe renal failure. * **TTP Triad/Pentad:** Remember that Plasmapheresis is the **gold standard** for Thrombotic Thrombocytopenic Purpura (TTP) [4]. * **Contraindication:** Do not use plasmapheresis if the patient has active sepsis or severe hemodynamic instability.

Question 210: Azotemia occurs when:

A. Glomerular filtration rate is 50% of normal.
B. Glomerular filtration rate is 80% of normal.
C. Glomerular filtration rate is 20% - 50% of normal. (Correct Answer)
D. Glomerular filtration rate is 25% of normal.

Explanation: **Explanation:** **Azotemia** is a biochemical abnormality characterized by elevation of blood urea nitrogen (BUN) and serum creatinine levels [1]. It is primarily a reflection of a decreased **Glomerular Filtration Rate (GFR)**. 1. **Why Option C is correct:** The kidneys possess a significant "renal reserve." In the early stages of renal impairment, the remaining functional nephrons undergo compensatory hypertrophy to maintain filtration. Consequently, serum markers like BUN and creatinine do not rise significantly until the GFR falls below **50% of its normal value**. Therefore, azotemia typically manifests when the GFR is in the range of **20% to 50%**. At this stage, patients are often asymptomatic but have measurable biochemical abnormalities [1]. 2. **Why other options are incorrect:** * **Option A & B (50% - 80%):** At these levels, the condition is often termed "diminished renal reserve." The GFR is reduced, but the compensatory mechanisms are sufficient to keep BUN and creatinine within the normal reference range. * **Option D (25%):** While azotemia is certainly present at 25%, this option is too narrow. The biochemical onset begins earlier (at the 50% threshold), making the range of 20-50% the more accurate clinical definition for the onset of azotemia. **NEET-PG High-Yield Pearls:** * **Azotemia vs. Uremia:** Azotemia is a purely biochemical finding [1]. **Uremia** occurs when azotemia is accompanied by clinical signs and symptoms (e.g., asterixis, pericarditis, encephalopathy) and systemic metabolic alterations [2]. * **Prerenal Azotemia:** Characterized by a **BUN:Creatinine ratio >20:1** and a Fractional Excretion of Sodium (**FeNa) <1%**, usually due to hypoperfusion. * **Renal Failure:** Defined when the GFR drops below **20%** of normal; **End-Stage Renal Disease (ESRD)** occurs when GFR is **<5%** of normal [1].

Practice by Chapter

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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