Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 71: What is the best prophylactic drug for a 60-year-old asthmatic female with microalbuminuria of 280mg?

A. Amiloride
B. Spironolactone
C. Enalapril
D. Telmisartan (Correct Answer)

Explanation: **Explanation:** The clinical presentation describes a patient with **Moderately Increased Albuminuria** (formerly microalbuminuria, defined as 30–300 mg/day) [1],[3]. In patients with albuminuria, the primary goal is to provide renoprotection by blocking the Renin-Angiotensin-Aldosterone System (RAAS) [1]. **Why Telmisartan is the Correct Answer:** Both ACE inhibitors (ACEIs) and Angiotensin II Receptor Blockers (ARBs) are first-line agents for renoprotection as they dilate the efferent arteriole, reducing intragulomerular pressure and protein excretion [1]. However, this patient is **asthmatic**. ACE inhibitors like **Enalapril** are associated with a dry cough (due to increased bradykinin and substance P) which can exacerbate respiratory symptoms or be confused with asthma symptoms [2]. **Telmisartan (an ARB)** provides the same renoprotective benefits without affecting bradykinin levels, making it the safer and preferred choice in an asthmatic patient [2]. **Analysis of Incorrect Options:** * **A & B (Amiloride & Spironolactone):** These are potassium-sparing diuretics. While Spironolactone has some role in resistant proteinuria, they are not first-line prophylactic agents for microalbuminuria and carry a high risk of hyperkalemia. * **C (Enalapril):** While effective for proteinuria, the risk of inducing a "bradykinin-mediated cough" [2] makes it less ideal than an ARB for a patient with a pre-existing reactive airway disease (asthma). **Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC)** for diabetic/hypertensive nephropathy: ACEIs or ARBs [1]. * **Mechanism:** Efferent arteriolar vasodilation → ↓ Glomerular capillary pressure [1],[2]. * **Contraindication:** Never combine ACEIs and ARBs (risk of hyperkalemia and acute kidney injury). * **Monitoring:** Always monitor serum creatinine and potassium levels within 1–2 weeks of starting RAAS blockers [2]. A rise in creatinine up to 30% is considered acceptable [1].

Question 72: Which of the following is NOT true about polycystic kidney disease?

A. Autosomal dominant inheritance
B. Proteinuria is typically less than 2 gm/day
C. It can lead to chronic renal failure (CRF)
D. Decompression of cysts leads to normal renal function (Correct Answer)

Explanation: **Explanation:** Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common inherited renal disorder [1]. Understanding its pathophysiology is crucial for the NEET-PG. **Why Option D is the correct answer (False statement):** Decompression of cysts (surgical or radiological) is performed primarily for symptomatic relief, such as intractable pain or pressure symptoms [1]. It **does not** restore or normalize renal function. The decline in GFR in ADPKD is due to the progressive replacement of normal renal parenchyma by cysts and subsequent interstitial fibrosis, which is irreversible [1]. **Analysis of other options:** * **Option A:** ADPKD follows an **autosomal dominant** inheritance pattern, primarily involving mutations in the *PKD1* (85%, Chromosome 16) and *PKD2* (15%, Chromosome 4) genes [1]. * **Option B:** Proteinuria in ADPKD is typically mild, usually **less than 2 g/day**. Nephrotic-range proteinuria is rare and suggests a secondary pathology (like FSGS). * **Option C:** ADPKD is a progressive condition. Approximately 50% of patients develop **End-Stage Renal Disease (ESRD)** or CRF by age 60, requiring dialysis or transplantation [1]. **Clinical Pearls for NEET-PG:** * **Extra-renal manifestations:** Hepatic cysts (most common), Berry aneurysms (Circle of Willis), Mitral Valve Prolapse (MVP), and diverticulosis. * **Diagnosis:** Ultrasonography is the first-line investigation (Ravine’s criteria). * **Management:** Tolvaptan (V2 receptor antagonist) is used to slow cyst growth and disease progression. * **Key Association:** Hypertension is often the earliest clinical sign, appearing even before a decline in GFR.

Question 73: Hypokalemia is seen in all the following conditions except?

A. Bartter syndrome
B. Hypokalemic periodic paralysis
C. 21 hydroxylase deficiency (Correct Answer)
D. Reninoma (juxtaglomerular cell tumor)

Explanation: ### Explanation The correct answer is **21-hydroxylase deficiency (Option C)**. #### 1. Why 21-hydroxylase deficiency is the correct answer: 21-hydroxylase deficiency is the most common cause of **Congenital Adrenal Hyperplasia (CAH)**. In this condition, there is a block in the conversion of progesterone to 11-deoxycorticosterone (the precursor to aldosterone). This leads to **mineralocorticoid deficiency (hypoaldosteronism)**. Since aldosterone is responsible for sodium reabsorption and potassium excretion in the distal tubule [1], its absence results in **Hyperkalemia**, hyponatremia, and metabolic acidosis. #### 2. Why the other options are incorrect: * **Bartter Syndrome (Option A):** This is a "loop-diuretic-like" defect in the thick ascending limb of the Henle's loop. It causes salt wasting, activation of the Renin-Angiotensin-Aldosterone System (RAAS), and subsequent **hypokalemia** and metabolic alkalosis. * **Hypokalemic Periodic Paralysis (Option B):** This is a channelopathy where potassium shifts from the extracellular fluid into the cells (intracellular shift), leading to acute episodes of **hypokalemia** and muscle weakness. * **Reninoma (Option D):** This is a rare juxtaglomerular cell tumor that secretes excessive renin. High renin leads to high aldosterone (Secondary Hyperaldosteronism), which causes sodium retention, hypertension, and significant **hypokalemia**. #### 3. NEET-PG High-Yield Pearls: * **CAH Rule of Thumb:** If the enzyme deficiency starts with **'1'** (11β-hydroxylase, 17α-hydroxylase), it causes **Hypertension** (due to mineralocorticoid excess). If it ends with **'1'** (21-hydroxylase), it causes **Hypotension/Salt-wasting**. * **11β-hydroxylase deficiency** causes hypokalemia because 11-deoxycorticosterone (which builds up) acts as a potent mineralocorticoid. * **Liddle Syndrome** is a "pseudo-hyperaldosteronism" that presents with hypertension and hypokalemia but with *low* renin and *low* aldosterone levels.

Question 74: Renal Tubular Acidosis (RTA) shows all except?

A. Urine pH always >5.5
B. Anion gap normal
C. Bicarbonaturia
D. Vitamin D deficiency (Correct Answer)

Explanation: **Explanation:** Renal Tubular Acidosis (RTA) is a group of disorders characterized by the inability of the renal tubules to either reabsorb bicarbonate or secrete hydrogen ions, despite a relatively preserved glomerular filtration rate. **Why Option D is the Correct Answer:** In RTA, the primary bone pathology is **Osteomalacia** (in adults) or **Rickets** (in children), but this is not due to a deficiency of Vitamin D itself. Instead, it is caused by the **buffering of chronic metabolic acidosis by bone salts** (leading to calcium loss) and, in Type 2 RTA, the loss of phosphate (phosphaturia). Vitamin D levels are typically normal, though its activation may be affected by systemic pH; however, "Vitamin D deficiency" is not a characteristic feature of RTA. **Analysis of Incorrect Options:** * **Option A (Urine pH >5.5):** This is a hallmark of **Type 1 (Distal) RTA**. Due to a defect in alpha-intercalated cells, the distal tubule cannot secrete H+ ions, making it impossible to acidify urine below pH 5.5, even in the presence of systemic acidosis [1]. * **Option B (Normal Anion Gap):** All forms of RTA are classic causes of **Normal Anion Gap Metabolic Acidosis (NAGMA)** [1]. The loss of HCO3- is compensated by a reciprocal increase in serum Chloride (Hyperchloremic metabolic acidosis) [2]. * **Option C (Bicarbonaturia):** This is the defining feature of **Type 2 (Proximal) RTA** [1]. The proximal tubule fails to reabsorb filtered HCO3-, leading to its excretion in the urine until a new, lower steady-state plasma level is reached [3]. **NEET-PG High-Yield Pearls:** * **Type 1 (Distal):** Associated with hypokalemia and **nephrolithiasis** (due to hypercalciuria and low urinary citrate). * **Type 2 (Proximal):** Associated with **Fanconi Syndrome** (glycosuria, phosphaturia, aminoaciduria). * **Type 4 (Hyperkalemic):** Associated with **Hypoaldosteronism** or aldosterone resistance (e.g., Diabetes Mellitus). It is the only RTA with high serum potassium.

Question 75: Which of the following is true about nephrogenic diabetes insipidus?

A. Renal tubule is unresponsive to ADH (Correct Answer)
B. There is central decrease in secretion of ADH
C. Serum sodium is low
D. Urine osmolality is increased after administration of ADH

Explanation: **Explanation:** **Nephrogenic Diabetes Insipidus (NDI)** is a clinical syndrome characterized by the inability of the kidneys to concentrate urine despite the presence of adequate levels of Antidiuretic Hormone (ADH/Vasopressin) [1]. 1. **Why Option A is Correct:** The fundamental defect in NDI is the **resistance of the renal collecting ducts to ADH**. This is usually due to mutations in the V2 receptor (X-linked recessive) or the Aquaporin-2 water channels, or acquired causes like Lithium toxicity and hypercalcemia [1], [2]. Since the tubules cannot respond to ADH, water reabsorption fails, leading to polyuria. 2. **Why Other Options are Incorrect:** * **Option B:** A central decrease in ADH secretion defines **Central Diabetes Insipidus**, not nephrogenic. In NDI, ADH levels are actually normal or elevated. * **Option C:** Patients lose free water in the urine, leading to hemoconcentration. Therefore, **Hypernatremia** (high serum sodium) is the classic finding, especially if the patient's thirst mechanism is impaired or access to water is restricted. * **Option D:** In the **Water Deprivation Test**, NDI is distinguished by a **failure to increase urine osmolality** after exogenous ADH (Desmopressin) administration [2], because the "end-organ" (kidney) is unresponsive. **High-Yield Clinical Pearls for NEET-PG:** * **Most common inherited cause:** X-linked recessive mutation in the **V2 receptor**. * **Most common drug-induced cause:** **Lithium** (it enters via ENaC channels and inhibits signaling). * **Electrolyte triggers:** **Hypercalcemia** and **Hypokalemia** can both induce NDI [2]. * **Treatment:** Thiazide diuretics (paradoxical effect), NSAIDs (Indomethacin), and a low-salt diet. Amiloride is specifically used for Lithium-induced NDI.

Question 76: Which investigation is most crucial for the diagnosis of idiopathic membranous glomerulopathy?

A. Antibody to PLA2R on podocytes (Correct Answer)
B. Kidney biopsy with immunofluorescent staining
C. C3, C4, and CH50 levels
D. c-ANCA titers

Explanation: **Membranous Nephropathy (MN)** is a leading cause of nephrotic syndrome in adults. It is characterized by the subepithelial deposition of immune complexes, leading to diffuse thickening of the glomerular basement membrane [1]. **1. Why Option A is Correct:** The discovery of the **Phospholipase A2 Receptor (PLA2R)** antibody has revolutionized the diagnosis of **Idiopathic (Primary) Membranous Glomerulopathy**. Approximately **70-80%** of patients with primary MN have circulating autoantibodies against the PLA2R antigen located on podocytes. This test is highly specific; a positive serum PLA2R antibody titer in a patient with nephrotic syndrome is virtually diagnostic of primary MN, often obviating the need for an invasive kidney biopsy in specific clinical scenarios. It also helps monitor disease activity and treatment response. **2. Why Other Options are Incorrect:** * **Option B:** While kidney biopsy was historically the "gold standard," the PLA2R antibody is now considered the most **crucial and specific** non-invasive biomarker for the *idiopathic* form. Biopsy shows "spikes" on Silver stain and granular IgG/C3 on IF [1], but it doesn't always distinguish primary from secondary causes as effectively as PLA2R. * **Option C:** C3 and C4 levels are typically **normal** in idiopathic MN. Low complement levels would suggest secondary causes like Lupus Nephritis (Class V). * **Option D:** c-ANCA is a marker for Granulomatosis with Polyangiitis (GPA), which typically presents as a Pauci-immune Crescentic Glomerulonephritis, not MN. **High-Yield Pearls for NEET-PG:** * **Most common cause of Primary MN:** Anti-PLA2R antibodies (70-80%). * **Second most common antibody:** Anti-THSD7A (Thrombospondin type-1 domain-containing 7A) – seen in ~5-10%. * **Rule of Thirds:** In MN, 1/3rd undergo spontaneous remission, 1/3rd persist with proteinuria, and 1/3rd progress to ESRD. * **Secondary MN Causes:** Think "Rule of M": **M**alignancy (Solid tumors), **M**edications (NSAIDs, Gold, Penicillamine), **M**icrobial (Hepatitis B, Syphilis), and **M**ixed Connective Tissue Disease (SLE).

Question 77: A 50-year-old diabetic patient presents with general malaise. On workup, his serum creatinine is 5.0 mg/dL and blood urea is 125 mg/dL. The urine MICRAL test is positive. Which of the following medications would be beneficial for this patient?

A. Diuretics (Correct Answer)
B. Cardio-selective beta-blocker
C. ACE inhibitor
D. Amiodarone

Explanation: The patient presents with advanced **Diabetic Kidney Disease (DKD)**, evidenced by a significantly elevated serum creatinine (5.0 mg/dL) and blood urea (125 mg/dL). These values indicate a severely reduced Glomerular Filtration Rate (GFR), likely placing the patient in **Stage 5 Chronic Kidney Disease (CKD)** [2]. **Why Diuretics are correct:** In advanced CKD (Stage 4 and 5), patients develop significant fluid retention and volume overload due to the kidney's inability to excrete sodium and water. **Loop diuretics** (e.g., Furosemide) are the mainstay of treatment to manage edema and hypertension in these patients [1]. While ACE inhibitors are Reno-protective in early stages, they are often contraindicated or used with extreme caution in advanced renal failure. **Analysis of Incorrect Options:** * **ACE Inhibitors (Option C):** While these are the "gold standard" for early DKD (to reduce proteinuria), they are generally **avoided or discontinued** when serum creatinine exceeds 3.0 mg/dL or in advanced CKD. They can cause a dangerous decline in GFR [2] and life-threatening **hyperkalemia**, which is already a risk in this patient. * **Cardio-selective Beta-blockers (Option B):** While used for hypertension, they are not the primary treatment for the metabolic and fluid complications of advanced renal failure. * **Amiodarone (Option D):** This is an anti-arrhythmic drug with no role in the management of diabetic nephropathy or azotemia. **Clinical Pearls for NEET-PG:** 1. **MICRAL Test:** A rapid immunoassay used to detect **Microalbuminuria** (30–300 mg/day), the earliest clinical sign of diabetic nephropathy [2]. 2. **Drug of Choice:** ACE inhibitors/ARBs are the drugs of choice for DKD *only* if the creatinine is <3 mg/dL. 3. **Kimmelstiel-Wilson (KW) Lesions:** The pathognomonic histological finding in diabetic nephropathy (nodular glomerulosclerosis). 4. **Management Shift:** In advanced CKD (Cr >5.0), the focus shifts from Reno-protection to managing complications (hyperkalemia, fluid overload, and preparation for dialysis).

Question 78: Dysmorphic RBCs with acute renal failure (ARF) are most commonly seen in which condition?

A. Glomerular disease (Correct Answer)
B. Renal carcinoma
C. Proximal tubule disease
D. Distal tubule disease

Explanation: The presence of **dysmorphic Red Blood Cells (RBCs)** in urine is a hallmark of **Glomerular disease** [1]. When RBCs pass through the damaged glomerular basement membrane (GBM) and travel through the varying osmotic gradients of the renal tubules, they undergo mechanical trauma and osmotic stress. This results in morphological changes such as blebbing, fragmentation, and the formation of **acanthocytes** (G1 cells), which are highly specific for glomerular bleeding. In the context of Acute Renal Failure (ARF), this finding strongly suggests **Acute Glomerulonephritis (AGN)** or Rapidly Progressive Glomerulonephritis (RPGN) [1]. **Analysis of Incorrect Options:** * **Renal Carcinoma:** This typically causes **isomorphic (normal-shaped) RBCs** because the bleeding occurs from the vascular supply of the tumor into the collecting system, bypassing the mechanical stress of the glomerular filter [1]. * **Proximal and Distal Tubule Disease:** While tubular diseases (like Acute Tubular Necrosis) are common causes of ARF, they typically present with **casts** (e.g., muddy brown casts) and tubular epithelial cells rather than dysmorphic RBCs. Hematuria is not a primary feature of isolated tubular injury. **NEET-PG High-Yield Pearls:** * **Acanthocytes:** The most specific type of dysmorphic RBC; if >5% of total urinary RBCs are acanthocytes, glomerular disease is highly likely. * **RBC Casts:** These are pathognomonic for glomerular hemorrhage. * **Isomorphic RBCs:** Suggest "urological" bleeding (stones, malignancy, or infections). * **Phase-contrast microscopy:** The gold standard method for identifying RBC morphology in urine.

Question 79: Microalbuminuria is defined as a urinary protein level in which range?

A. 30-200 mg/day
B. 30-300 mg/day (Correct Answer)
C. 30-150 mg/day
D. 30-100 mg/day

Explanation: **Explanation:** Microalbuminuria refers to a level of albumin excretion that is higher than normal but below the detection limit of a standard urine dipstick [1]. It is a critical clinical marker for early-stage diabetic nephropathy and cardiovascular risk [1]. 1. **Why Option B is Correct:** The standard clinical definition of microalbuminuria is a urinary albumin excretion rate of **30–300 mg/day** (or 20–200 µg/min). In a spot urine sample, this corresponds to an **Albumin-to-Creatinine Ratio (ACR) of 30–300 mg/g**. Values below 30 mg/day are considered normal, while values above 300 mg/day are classified as "macroalbuminuria" or overt proteinuria [2]. 2. **Why Other Options are Incorrect:** * **Option A (30-200 mg/day):** This is a common distractor; while 200 µg/min is the upper limit in timed collections, the daily excretion limit is 300 mg. * **Options C & D:** These ranges are arbitrarily lower and do not align with the established KDIGO or ADA guidelines for defining incipient nephropathy. **Clinical Pearls for NEET-PG:** * **Screening:** The most sensitive and preferred screening method is the **Spot Morning Urine Albumin-to-Creatinine Ratio (ACR)**. [1] * **Diagnosis:** Diagnosis requires at least **two out of three** positive specimens collected over a 3- to 6-month period, as transient elevations can occur due to exercise, fever, or heart failure. * **Significance:** It is the earliest sign of diabetic nephropathy and is reversible with strict glycemic control and **ACE inhibitors or ARBs**, which provide Reno-protection. [2]

Question 80: HIV-induced nephropathy is more common in which of the following subsets of HIV patients?

A. Homosexuals
B. Heterosexuals
C. Intravenous drug abusers (Correct Answer)
D. Congenital HIV

Explanation: **Explanation:** **HIV-Associated Nephropathy (HIVAN)** is a classic form of renal involvement in HIV patients, characterized histologically by **Collapsing Focal Segmental Glomerulosclerosis (FSGS)** [1]. **Why Intravenous Drug Abusers (IVDAs) are the correct answer:** Epidemiological studies have consistently shown that HIVAN has a strong predilection for specific demographics. It is most common in **African Americans** (due to the APOL1 genetic risk variant) and **Intravenous Drug Abusers** [2]. The association with IVDAs is likely multifactorial, involving both the direct cytopathic effects of HIV on the glomerular epithelium and the potential synergistic renal damage caused by injected substances (like heroin, which independently causes "Heroin Nephropathy"). **Analysis of Incorrect Options:** * **A & B (Homosexuals and Heterosexuals):** While HIV is frequently transmitted via sexual routes, these subsets do not show a disproportionately higher incidence of HIVAN compared to the IVDA population, unless they also belong to the high-risk African American genotype. * **D (Congenital HIV):** While children with congenital HIV can develop renal disease, the classic "HIVAN" phenotype is significantly more prevalent in the adult IVDA population. **NEET-PG High-Yield Pearls:** * **Histology:** Collapsing FSGS is the hallmark (look for "wrinkling and collapse of the glomerular basement membrane") [1]. * **Clinical Presentation:** Rapidly progressive renal failure, heavy proteinuria (nephrotic range), and **normal-sized or enlarged kidneys** on ultrasound (unlike most chronic kidney diseases where kidneys shrink). * **Treatment:** Highly Active Antiretroviral Therapy (HAART) is the mainstay of treatment and can slow progression. * **Genetic Link:** Strongly associated with **APOL1 gene** polymorphisms on chromosome 22.

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Acute Kidney Injury

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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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