Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 141: Which one of the following statements is false with regard to pyuria in children?

A. Presence of more than 5 WBC/hpf for girls and more than 3 WBC/hpf for boys (Correct Answer)
B. Infection can occur without pyuria
C. Pyuria may be present without urinary tract infection
D. Isolated pyuria is neither confirmatory nor diagnostic for urinary tract infection

Explanation: **Explanation:** The correct answer is **Option A** because the definition provided is outdated and clinically inaccurate. In modern pediatric practice, pyuria is defined as the presence of **>5 WBCs per high-power field (hpf)** in a centrifuged urine sample, or **>10 WBCs/mm³** in uncentrifuged urine using a hemocytometer. There is **no gender-based distinction** (3 for boys vs. 5 for girls) in the threshold for defining pyuria in children. **Analysis of other options:** * **Option B (Infection without pyuria):** This is true. Pyuria may be absent in early stages of UTI, in children with neutropenia, or in infections caused by organisms that do not elicit a strong inflammatory response. * **Option C (Pyuria without UTI):** This is true. "Sterile pyuria" can occur in conditions like Kawasaki disease, viral infections, renal tuberculosis, urolithiasis, or after recent antibiotic use. * **Option D (Isolated pyuria):** This is true. Pyuria is merely a marker of inflammation, not infection. The gold standard for diagnosing UTI remains a **significant colony count on urine culture**. **High-Yield Clinical Pearls for NEET-PG:** * **Most common cause of UTI in children:** *E. coli*. * **Sterile Pyuria in Pediatrics:** Classically associated with **Kawasaki Disease** (WBCs are typically of urethral origin). * **Nitrite Test:** Highly specific but has low sensitivity in infants because they empty their bladders frequently, preventing the 4-hour incubation required for bacteria to convert nitrates to nitrites. * **Gold Standard Diagnosis:** Urine culture obtained via suprapubic aspiration (any growth is significant) or transurethral catheterization (>50,000 CFU/ml).

Question 142: Hypokalemia in an infant may be due to all of the following except?

A. Adrenal tumor
B. Acute renal failure (Correct Answer)
C. Thiazide therapy
D. Diarrhea

Explanation: ### Explanation The correct answer is **B. Acute renal failure**. In **Acute Renal Failure (ARF)**, specifically during the oliguric phase, the kidneys are unable to excrete potassium effectively. This leads to **hyperkalemia** (elevated serum potassium), which is a life-threatening complication of renal failure. Hypokalemia is only seen in the later "diuretic phase" of recovery, but the hallmark of acute renal insult is potassium retention. **Analysis of Incorrect Options:** * **Adrenal tumor:** Specifically, tumors like Conn’s syndrome (Primary Hyperaldosteronism) or those causing Cushing’s syndrome lead to excess mineralocorticoid activity. Aldosterone acts on the distal tubules to reabsorb sodium and **excrete potassium**, resulting in hypokalemia. * **Thiazide therapy:** Thiazide diuretics inhibit the NaCl symporter in the distal convoluted tubule. This increases sodium delivery to the collecting ducts, where it is exchanged for potassium, leading to **urinary potassium wasting** and hypokalemia. * **Diarrhea:** This is a common cause of hypokalemia in infants. Gastrointestinal fluids are rich in potassium and bicarbonate; excessive loss leads to both dehydration and significant **hypokalemia**. **NEET-PG High-Yield Pearls:** * **ECG in Hypokalemia:** Look for flattened T-waves, prominent **U-waves**, and ST-segment depression. * **ECG in Hyperkalemia:** Look for **tall tented T-waves**, widened QRS, and loss of P-waves. * **Bartter and Gitelman Syndromes:** These are important pediatric genetic causes of hypokalemia associated with metabolic alkalosis and normal blood pressure. * **Rule of Thumb:** Most "renal failure" questions in exams assume the oliguric phase unless "diuretic phase" is explicitly mentioned.

Question 143: A 10-year-old boy presents with cola-colored urine, oliguria for 3 days, facial puffiness, edema, and hypertension. Urine albumin is positive, and C3 levels are reduced. His blood pressure is 130/80 mmHg. He had a skin infection two weeks prior. Which of the following is true about this condition?

A. Renal biopsy is required in all cases.
B. C3 levels return to normal in 6-8 weeks. (Correct Answer)
C. Cyclosporine is the treatment of choice.
D. The most common age group involved is 1-4 years.

Explanation: The clinical presentation of cola-colored urine, hypertension, edema, and low C3 levels following a skin infection (impetigo) points to **Post-Streptococcal Glomerulonephritis (PSGN)**. ### **Explanation of Options** * **Correct Answer (B):** In PSGN, the alternative complement pathway is activated, leading to low C3 levels. A hallmark of PSGN is that **C3 levels return to normal within 6–8 weeks**. If C3 remains low beyond 8 weeks, alternative diagnoses like Membranoproliferative Glomerulonephritis (MPGN) or Lupus Nephritis must be considered. * **Option A:** Renal biopsy is **not** routinely required. It is only indicated if there is atypical presentation (e.g., normal C3, persistent hematuria/proteinuria, or rapidly deteriorating renal function). * **Option C:** The treatment is primarily **supportive** (fluid restriction, diuretics for edema, and antihypertensives like CCBs). Immunosuppressants like Cyclosporine have no role in PSGN. * **Option D:** PSGN typically affects school-aged children. The most common age group is **5–12 years**; it is uncommon under the age of 3. ### **High-Yield Clinical Pearls for NEET-PG** * **Latent Period:** 1–2 weeks after pharyngitis; 3–6 weeks after skin infection (pyoderma). * **Diagnosis:** Low C3, elevated ASO titer (more common in pharyngitis), and elevated Anti-DNase B (more sensitive for skin infections). * **Microscopy:** Light microscopy shows "Starry sky" appearance or "Lumpy-bumpy" deposits. Electron microscopy shows characteristic **sub-epithelial humps**. * **Prognosis:** Excellent in children (>95% complete recovery); worse in adults. Hematuria may persist for up to 1 year.

Question 144: What is the presenting manifestation of Alport syndrome?

A. Hematuria (Correct Answer)
B. Proteinuria
C. Oliguria
D. Sensorineural deafness

Explanation: **Explanation:** **Alport Syndrome** is a hereditary type IV collagen disorder (most commonly X-linked dominant) caused by mutations in the *COL4A3, COL4A4,* or *COL4A5* genes. This leads to structural defects in the glomerular basement membrane (GBM), cochlea, and lens. 1. **Why Hematuria is Correct:** **Persistent microscopic or gross hematuria** is the hallmark and earliest presenting manifestation of Alport syndrome, often appearing in early childhood. The defective type IV collagen causes the GBM to be thin and fragile initially, leading to the leakage of red blood cells into the urine. 2. **Why Other Options are Incorrect:** * **Proteinuria:** While proteinuria develops as the disease progresses and signifies worsening renal function (eventually leading to Nephrotic range proteinuria), it is rarely the *initial* presenting sign. * **Oliguria:** This is a feature of acute kidney injury or end-stage renal disease (ESRD). It is a late-stage complication rather than a presenting symptom. * **Sensorineural Deafness:** Although a classic extra-renal feature of Alport syndrome, it typically manifests in late childhood or adolescence (usually after the onset of hematuria). It is a diagnostic clue but not the primary presenting manifestation. **High-Yield Clinical Pearls for NEET-PG:** * **Electron Microscopy (Gold Standard):** Shows a characteristic **"Basket-weave appearance"** due to irregular thickening, thinning, and splitting of the GBM. * **Ocular Findings:** **Anterior Lenticonus** (pathognomonic) and perimacular "fleck" retinopathy. * **Inheritance:** 80% are X-linked Dominant (males are more severely affected). * **Rule of 3:** Alport syndrome affects the **Kidneys** (Hematuria), **Ears** (SNHL), and **Eyes** (Lenticonus).

Question 145: Hypertensive crises in younger children are usually secondary to an underlying disease. What is the commonest cause of systemic hypertension in children?

A. Coarctation of aorta
B. Acute glomerulonephritis (Correct Answer)
C. Nephrotic syndrome
D. Lactic acidosis

Explanation: **Explanation:** In the pediatric population, hypertension is predominantly **secondary** rather than essential. The most common cause of systemic hypertension in children is **Renal Parenchymal Disease**, accounting for approximately 70-80% of cases. Among these, **Acute Glomerulonephritis (AGN)**—specifically Post-Streptococcal Glomerulonephritis (PSGN)—is the leading cause. **Why Acute Glomerulonephritis is correct:** The pathophysiology involves immune-complex deposition in the glomeruli, leading to a sudden decrease in the Glomerular Filtration Rate (GFR). This results in **salt and water retention**, leading to volume expansion and circulatory overload, which manifests clinically as hypertension, edema, and hematuria. **Analysis of Incorrect Options:** * **Coarctation of Aorta:** While a classic cause of upper limb hypertension in children, it is less common than renal causes. It should be suspected if there is a significant blood pressure differential between upper and lower limbs and diminished femoral pulses. * **Nephrotic Syndrome:** Hypertension is not a primary feature of minimal change disease (the most common type). While it can occur in certain variants (like FSGS), it is far less frequent than in nephritic syndromes like AGN. * **Lactic Acidosis:** This is a metabolic derangement often associated with shock or metabolic errors; it typically presents with hypotension or cardiovascular collapse rather than systemic hypertension. **High-Yield Clinical Pearls for NEET-PG:** 1. **Age-wise causes:** In newborns, renal artery thrombosis is common; in adolescents, essential hypertension becomes more prevalent. 2. **Gold Standard:** The most accurate way to diagnose pediatric hypertension is by using age, sex, and height-based **BP centile charts**. 3. **Rule of Thumb:** Any child presenting with a hypertensive crisis and "cola-colored urine" should be evaluated for PSGN first.

Question 146: Which of the following is a feature of Hemolytic Uremic Syndrome in children?

A. Helmet cells in peripheral blood smear
B. Thrombocytopenia (Correct Answer)
C. Positive Coombs test
D. Hypothyroidism

Explanation: **Explanation:** Hemolytic Uremic Syndrome (HUS) is a clinical triad characterized by **Microangiopathic Hemolytic Anemia (MAHA)**, **Thrombocytopenia**, and **Acute Kidney Injury (AKI)**. It most commonly follows a prodrome of bloody diarrhea caused by Shiga toxin-producing *E. coli* (O157:H7). **Why Option B is Correct:** Thrombocytopenia occurs due to the **sequestration and consumption of platelets** within the damaged microvasculature. The Shiga toxin causes endothelial injury, leading to the formation of platelet-rich microthrombi in small vessels (primarily in the kidneys). This "consumptive thrombocytopenia" results in a low systemic platelet count, typically below 150,000/mm³. **Analysis of Incorrect Options:** * **Option A (Helmet cells):** While helmet cells (schistocytes) are a hallmark of HUS, the question asks for a "feature." In many standardized formats, if multiple features are present, the most definitive clinical triad component is prioritized. However, note that **Helmet cells are indeed present**; if this were a "multiple correct" style, A would also be right. In a single-best-answer context, thrombocytopenia is a core definition of the HUS triad. * **Option C (Positive Coombs test):** HUS is a **Coombs-negative** hemolytic anemia. The hemolysis is mechanical (fragmentation of RBCs as they pass through fibrin clots), not immune-mediated. * **Option D (Hypothyroidism):** There is no established clinical association between HUS and thyroid dysfunction. **NEET-PG High-Yield Pearls:** * **Classic Triad:** Anemia + Thrombocytopenia + Renal Failure. * **Peripheral Smear:** Shows Schistocytes (Helmet cells) and low platelets. * **Coagulation Profile:** PT, aPTT, and INR are typically **normal** (distinguishing HUS from DIC). * **Management:** Primarily supportive (fluid/electrolyte balance, dialysis). **Antibiotics and anti-motility agents are contraindicated** as they may increase toxin release.

Question 147: In children, what is the definition of renal failure in terms of urine output?

A. Less than 0.3 ml/kg/hr (Correct Answer)
B. Less than 0.5 ml/kg/hr
C. Less than 0.8 ml/kg/hr
D. Less than 1 ml/kg/hr

Explanation: In pediatric nephrology, the definition of renal failure (specifically oliguria and anuria) is strictly categorized based on urine output (UOP) over a specific duration. **Explanation of the Correct Answer:** **Option A (< 0.3 ml/kg/hr)** is the correct definition for **renal failure** (Stage 3 Acute Kidney Injury) according to the **pRIFLE criteria** (Pediatric Risk, Injury, Failure, Loss, and End-stage renal disease). Specifically, "Failure" is defined as UOP < 0.3 ml/kg/hr for 24 hours or anuria for 12 hours. This threshold represents a critical decline in glomerular filtration where the kidneys can no longer maintain fluid and electrolyte homeostasis. **Analysis of Incorrect Options:** * **Option B (< 0.5 ml/kg/hr):** This is the definition of **Oliguria** in children and corresponds to the "Injury" stage (Stage 2) of AKI if it persists for 12 hours. * **Option C (< 0.8 ml/kg/hr):** This value does not correspond to a standard clinical definition for renal failure or oliguria in pediatrics. * **Option D (< 1 ml/kg/hr):** In **neonates**, oliguria is often defined as < 1 ml/kg/hr. However, for general pediatric renal failure definitions, the pRIFLE/KDIGO criteria of < 0.3 ml/kg/hr is the standard. **High-Yield Clinical Pearls for NEET-PG:** * **pRIFLE Criteria:** Uses Serum Creatinine (estimated CrCl) and Urine Output. "Risk" is UOP < 0.5 ml/kg/hr for 8 hours. * **Neonatal Oliguria:** Defined as < 1 ml/kg/hr. * **Most Common Cause:** Prerenal azotemia (dehydration) is the most common cause of AKI in children. * **Formula:** Estimated GFR in children (Schwartz Formula) = $k \times \text{Height (cm)} / \text{Serum Creatinine}$.

Question 148: In nephritic syndrome, which of the following features indicates a poor prognosis?

A. Selective proteinuria (Correct Answer)
B. Hematuria
C. Hypertension
D. Membranoproliferative histopathology

Explanation: **Explanation** In the context of glomerular diseases, the presence of **selective proteinuria** is a hallmark of **Nephrotic Syndrome** (specifically Minimal Change Disease), not Nephritic Syndrome. Nephritic syndrome is typically characterized by non-selective proteinuria due to significant basement membrane damage. Therefore, finding selective proteinuria in a patient presenting with a nephritic picture is an atypical finding that suggests a complex or overlapping pathology, often correlating with a poorer response to standard therapy and a worse long-term prognosis. **Analysis of Options:** * **A. Selective Proteinuria (Correct):** Selective proteinuria (loss of low-molecular-weight proteins like albumin) indicates intact glomerular charge selectivity but lost size selectivity. In nephritic conditions, its presence often points toward underlying structural damage or a transition to chronic glomerular disease, which carries a worse prognosis than typical transient post-streptococcal glomerulonephritis (PSGN). * **B. Hematuria:** This is a cardinal feature of nephritic syndrome (often "coke-colored" urine). While it defines the condition, it is usually transient and does not independently indicate a poor prognosis. * **C. Hypertension:** Common in the acute phase of nephritic syndrome due to fluid overload. In children (e.g., PSGN), it is usually manageable and resolves as the inflammation subsides. * **D. Membranoproliferative histopathology:** While MPGN has a guarded prognosis, the question specifically highlights "Selective Proteinuria" as the clinical/biochemical marker indicating a poor prognostic shift in the nephritic spectrum. **High-Yield Clinical Pearls for NEET-PG:** * **Selective Proteinuria:** Measured by the **Cameron Index** (IgG/Transferrin ratio). A ratio <0.1 indicates high selectivity. * **Most common cause of Nephritic Syndrome in children:** Post-streptococcal glomerulonephritis (PSGN). * **Prognostic Marker:** Persistent low C3 levels beyond 8 weeks in suspected PSGN should prompt a biopsy to rule out MPGN.

Question 149: All of the following are associated with low complement levels except?

A. Lupus nephritis
B. Mesangiocapillary glomerulonephritis
C. Diarrhea-associated hemolytic uremic syndrome (Correct Answer)
D. Post-infectious glomerulonephritis

Explanation: ### Explanation The measurement of serum complement levels (specifically C3 and C4) is a critical diagnostic step in pediatric nephrology to differentiate between various types of glomerulonephritis (GN). **Why Option C is Correct:** **Diarrhea-associated Hemolytic Uremic Syndrome (D+ HUS)** is typically caused by Shiga toxin-producing *E. coli* (STEC). The pathophysiology involves direct endothelial injury and microvascular thrombosis rather than immune complex-mediated complement consumption. Therefore, **complement levels remain normal** in D+ HUS. *Note:* In contrast, "Atypical HUS" (non-diarrheal) is often associated with genetic mutations in the alternative complement pathway, though serum C3 levels may still be normal in many cases. **Why the Other Options are Incorrect:** * **Post-infectious GN (PSGN):** Characterized by **low C3** and normal C4. This occurs due to the activation of the alternative complement pathway. Levels typically normalize within 6–8 weeks. * **Lupus Nephritis:** A classic immune complex-mediated disease that activates the classical pathway, leading to **low C3 and low C4**. * **Mesangiocapillary (Membranoproliferative) GN:** * Type I: Low C3 and low C4 (Classical pathway). * Type II (Dense Deposit Disease): Low C3 and normal C4 (Alternative pathway due to C3 nephritic factor). **High-Yield Clinical Pearls for NEET-PG:** 1. **Low C3 + Normal C4:** PSGN, MPGN Type II. 2. **Low C3 + Low C4:** Systemic Lupus Erythematosus (SLE), MPGN Type I, Subacute Bacterial Endocarditis, Cryoglobulinemia. 3. **Normal Complement GN:** IgA Nephropathy (most common worldwide), Henoch-Schönlein Purpura (HSP), Minimal Change Disease, and Alport Syndrome. 4. If C3 remains low beyond 8 weeks in a suspected PSGN case, consider a renal biopsy to rule out MPGN.

Question 150: A child with a history of recurrent throat infections presents with hematuria and proteinuria. The last infection was 3 weeks prior to presentation. What is the most likely diagnosis?

A. Berger's disease
B. Henoch-Schönlein purpura
C. Membranoproliferative glomerulonephritis
D. Poststreptococcal glomerulonephritis (Correct Answer)

Explanation: **Explanation** The correct answer is **Poststreptococcal Glomerulonephritis (PSGN)**. **Why PSGN is correct:** PSGN is the most common cause of acute nephritic syndrome in children. It typically follows an infection with Group A Beta-hemolytic Streptococcus (GABHS). The hallmark of PSGN is the **latent period** between the infection and the onset of renal symptoms (hematuria, proteinuria, edema, and hypertension). For post-pharyngeal infections, this period is typically **1–3 weeks**, matching the 3-week timeline in this clinical scenario. **Why other options are incorrect:** * **Berger’s Disease (IgA Nephropathy):** This is the most common cause of glomerulonephritis worldwide. However, it presents as **synpharyngitic hematuria**, meaning the hematuria occurs simultaneously or within 1–2 days of the infection, lacking the long latent period seen in PSGN. * **Henoch-Schönlein Purpura (HSP):** While it involves IgA deposition, it is a systemic vasculitis characterized by a classic tetrad: palpable purpura (usually on lower limbs), arthralgia, abdominal pain, and renal involvement. * **Membranoproliferative Glomerulonephritis (MPGN):** This is a chronic condition that can present with nephritic or nephrotic features but is not typically triggered by a specific acute streptococcal infection with a distinct latent period. **High-Yield Clinical Pearls for NEET-PG:** * **Low C3 levels:** A key diagnostic marker in PSGN; complement levels usually return to normal within 6–8 weeks. * **ASO Titer:** Elevated after pharyngeal infection; **Anti-DNase B** is more sensitive for skin infections (impetigo). * **Microscopy:** Look for "Lumpy-bumpy" or "Starry sky" appearance on Immunofluorescence (IgG and C3 deposits). * **Electron Microscopy:** Pathognomonic **Subepithelial humps**.

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Urinary Tract Infections

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Vesicoureteral Reflux

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Glomerulonephritis

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Nephrotic Syndrome

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Acute Kidney Injury

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Chronic Kidney Disease

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Renal Tubular Disorders

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Congenital Anomalies of the Kidney

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Hydronephrosis

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Hypertension in Children

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Hemolytic Uremic Syndrome

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Renal Replacement Therapy in Children

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Nephrology — MCQs

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