Nephrology — MCQs

Nephrology Indian Medical PG Practice Questions and MCQs

Question 101: Lowe's syndrome is characterized by the following, except:

A. Hypophosphatemic rickets
B. Undescended testes (Correct Answer)
C. Defect in the CNS and eyes
D. Aminoaciduria

Explanation: **Lowe’s Syndrome**, also known as **Oculocerebrorenal Syndrome**, is a rare X-linked recessive disorder caused by a mutation in the *OCRL1* gene. This gene encodes a phosphatase enzyme found in the Golgi apparatus, and its deficiency leads to multisystemic dysfunction primarily affecting the eyes, brain, and kidneys. ### **Explanation of Options** * **Correct Answer (B) Undescended testes:** This is the correct choice because cryptorchidism (undescended testes) is **not** a characteristic feature of Lowe’s syndrome. While the syndrome involves multiple systems, the reproductive system is typically not affected in this specific manner. * **Option (A) Hypophosphatemic rickets:** Lowe’s syndrome causes **proximal renal tubular acidosis (Fanconi Syndrome)**. The resulting renal phosphate wasting leads to hypophosphatemia, which manifests clinically as rickets in children. * **Option (C) Defect in the CNS and eyes:** This is a hallmark of the disease. Ocular findings include **bilateral congenital cataracts** (present in 100% of cases) and glaucoma. CNS involvement presents as profound hypotonia ("floppy baby"), intellectual disability, and behavioral issues. * **Option (D) Aminoaciduria:** As part of the generalized **Fanconi Syndrome**, the proximal tubule fails to reabsorb solutes, leading to aminoaciduria, glucosuria, and low-molecular-weight proteinuria. ### **High-Yield Clinical Pearls for NEET-PG** * **Inheritance:** X-linked Recessive (primarily affects males). * **The "Triad":** Congenital cataracts, Neonatal hypotonia, and Renal Fanconi syndrome. * **Biochemical Marker:** Elevated levels of lysosomal enzymes in the serum and metabolic acidosis with a normal anion gap. * **Diagnosis:** Confirmed by measuring **inositol polyphosphate 5-phosphatase** activity in skin fibroblasts or through *OCRL* gene sequencing.

Question 102: A child presents with recurrent muscle cramps and spasms. Laboratory analysis reveals hypokalemia, metabolic alkalosis, hypocalciuria, and increased urinary magnesium. What is the most probable diagnosis?

A. Bartter syndrome
B. Gittelman syndrome (Correct Answer)
C. Liddle syndrome
D. None of the above

Explanation: **Explanation:** The clinical presentation of **Gittelman syndrome** is characterized by the triad of hypokalemic metabolic alkalosis, **hypocalciuria**, and **hypomagnesemia** (due to renal magnesium wasting). It is an autosomal recessive disorder caused by a mutation in the **SLC12A3 gene**, leading to a defect in the **Thiazide-sensitive Sodium-Chloride (NaCl) cotransporter** in the Distal Convoluted Tubule (DCT). This mimics the chronic use of Thiazide diuretics. **Why the other options are incorrect:** * **Bartter Syndrome:** While it also presents with hypokalemic metabolic alkalosis, it is characterized by **hypercalciuria** (increased urinary calcium) and often presents earlier in infancy with polyuria and growth retardation. It mimics the effect of **Loop diuretics** (defect in the NKCC2 transporter in the Thick Ascending Limb). * **Liddle Syndrome:** This is a "pseudo-aldosteronism" caused by overactivity of ENaC channels. While it causes hypokalemia and metabolic alkalosis, it is distinguished by **hypertension** and low renin/aldosterone levels. Gittelman patients are typically normotensive or hypotensive. **High-Yield NEET-PG Pearls:** * **Gittelman vs. Bartter:** The "Gold Standard" differentiator is urinary calcium. **Gittelman = Low Calcium**; **Bartter = High Calcium.** * **Mnemonic:** **G**ittelman is like **G**entle (presents later in childhood/adolescence) and associated with low **M**agnesium (**M**agnesium starts with 'M', the next letter after 'L' in Gitte**l**man). * **Metabolic Profile:** Both Bartter and Gittelman present with **increased Renin and Aldosterone** (Secondary Hyperaldosteronism) due to volume depletion.

Question 103: Which one of the following statements is false with regard to pyuria in children?

A. Presence of more than 5 white blood cells/high power field for girls and more than 3 white blood cells/high power field 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 definition of pyuria in children is standardized regardless of gender. Pyuria is defined as the presence of **>5 white blood cells (WBCs) per high-power field (hpf)** in a centrifuged urine sample, or **>10 WBCs/mm³** in uncentrifuged urine using a counting chamber. **1. Why Option A is False (The Correct Answer):** The statement incorrectly suggests different thresholds for boys and girls. In pediatric nephrology, the threshold for pyuria is **uniform (>5 WBCs/hpf)**. Differentiating by gender is not a standard clinical practice for defining pyuria. **2. Analysis of Other Options:** * **Option B (Infection without pyuria):** This is true. Approximately 10-20% of children with a culture-proven Urinary Tract Infection (UTI) may not exhibit pyuria, especially if the infection is early or if the patient is neutropenic. * **Option C (Pyuria without UTI):** This is true. "Sterile pyuria" can occur in conditions like viral infections, Kawasaki disease, renal tuberculosis, urolithiasis, or even following recent antibiotic use. * **Option D (Isolated pyuria is not diagnostic):** This is true. Pyuria is a marker of inflammation, not necessarily infection. The **gold standard** for diagnosing UTI remains a significant colony count on **urine culture**. **Clinical Pearls for NEET-PG:** * **Gold Standard Diagnosis:** Urine culture (significant bacteriuria). * **Most Common Organism:** *E. coli* (80-90%). * **Nitrite Test:** Highly specific but has low sensitivity in infants because they empty their bladders frequently (nitrites require ~4 hours of bladder incubation). * **Leukocyte Esterase:** A rapid indirect marker for pyuria. * **Kawasaki Disease:** Classically associated with sterile pyuria (WBCs are of urethral origin).

Question 104: What is the best initial treatment for enuresis?

A. Oxybutinin
B. Desmopressin
C. Bed alarm (Correct Answer)
D. Imipramine

Explanation: **Explanation:** Monosymptomatic nocturnal enuresis (bedwetting in children >5 years without daytime symptoms) is primarily managed through behavioral interventions and conditioning. **Why Bed Alarm is Correct:** The **bedwetting alarm** is considered the **most effective long-term treatment** and the best initial active intervention. It works on the principle of **classical conditioning**: a sensor detects moisture and triggers an alarm, waking the child to void in the toilet. Over time, the child learns to associate bladder fullness with waking up. It has a higher long-term cure rate and lower relapse rate compared to pharmacological options. **Why Incorrect Options are Wrong:** * **Oxybutynin (A):** This is an anticholinergic used for "non-monosymptomatic" enuresis (children with daytime urgency or overactive bladder). It is not the first-line for isolated nocturnal bedwetting. * **Desmopressin (B):** An ADH analogue that reduces urine production. While it provides rapid symptomatic relief (useful for sleepovers), it has a **high relapse rate** once discontinued and is generally considered second-line or used as an adjunct to alarms. * **Imipramine (D):** A tricyclic antidepressant once commonly used, it is now rarely recommended due to its narrow therapeutic index and the risk of **cardiotoxicity/fatal arrhythmia** in overdose. **Clinical Pearls for NEET-PG:** 1. **Initial Step:** Always start with **behavioral advice** (limiting evening fluids, scheduled voiding) and reassurance. If these fail, the **bed alarm** is the next best step. 2. **Age Criteria:** Enuresis is only diagnosed if the child is **≥5 years** of age. 3. **Success Metric:** Alarm therapy usually requires 3–4 months of consistent use to be effective. 4. **Rule Out:** Before starting treatment, always rule out secondary causes like UTI, Diabetes Mellitus, or Constipation.

Question 105: What is the drug of choice for nocturnal enuresis in children?

A. Desmopressin (Correct Answer)
B. Imipramine
C. Amitriptyline
D. Benzodiazepines

Explanation: **Explanation:** **Nocturnal Enuresis** (bedwetting) is defined as involuntary voiding of urine during sleep in children aged ≥5 years. **Why Desmopressin is the Correct Answer:** Desmopressin (DDAVP), a synthetic analogue of Antidiuretic Hormone (ADH), is the **first-line pharmacological treatment**. It works by binding to V2 receptors in the renal collecting ducts, increasing water reabsorption and reducing urine volume produced overnight. It is preferred due to its rapid onset of action and superior safety profile compared to older alternatives. **Analysis of Incorrect Options:** * **Imipramine & Amitriptyline:** These are Tricyclic Antidepressants (TCAs). While effective in increasing bladder capacity and anticholinergic action, they are **second or third-line** due to the risk of cardiotoxicity (arrhythmias) and potential lethality in accidental overdose. * **Benzodiazepines:** These have no role in the management of enuresis; they may actually worsen the condition by deepening sleep and causing muscle relaxation. **High-Yield Clinical Pearls for NEET-PG:** * **Initial Management:** The first step is always **behavioral modification** (fluid restriction before bed, bladder training) and **Enuresis Alarms** (most effective long-term therapy with the lowest relapse rate). * **Drug of Choice:** Desmopressin is the drug of choice when alarms fail or for short-term relief (e.g., sleepovers). * **Caution:** When using Desmopressin, fluid intake must be restricted 1 hour before and 8 hours after administration to prevent **hyponatremia** and water intoxication. * **Rule Out:** Always exclude secondary causes like UTI, Diabetes Mellitus, or Constipation before diagnosing primary enuresis.

Question 106: What is the treatment of choice for nocturnal enuresis?

A. Oxybutynin
B. Imipramine
C. Desmopressin
D. Behavioral therapy (Correct Answer)

Explanation: **Explanation:** Nocturnal enuresis (bedwetting) is defined as involuntary voiding of urine during sleep in children aged ≥5 years. The management follows a stepped approach, prioritizing non-pharmacological interventions. **Why Behavioral Therapy is the Correct Answer:** Behavioral therapy is the **first-line treatment of choice**. It begins with **lifestyle modifications** (limiting evening fluid intake, scheduled voiding before bed) and **positive reinforcement** (star charts). If these fail, the **enuresis alarm** (conditioning therapy) is considered the most effective long-term treatment with the lowest relapse rates. It works by conditioning the child to wake up when the bladder is full. **Analysis of Incorrect Options:** * **Oxybutynin (A):** An anticholinergic used primarily for "overactive bladder" or daytime urgency. It is not first-line for isolated nocturnal enuresis. * **Imipramine (B):** A tricyclic antidepressant once commonly used; however, it is now a **last-resort** due to its narrow therapeutic index and risk of fatal cardiac arrhythmias in overdose. * **Desmopressin (C):** An ADH analogue that reduces urine production. While it provides rapid symptomatic relief (useful for sleepovers), it has a **high relapse rate** once discontinued and is generally reserved for cases resistant to behavioral therapy. **NEET-PG High-Yield Pearls:** * **Definition Age:** Must be at least 5 years old (developmental age). * **Most Common Cause:** Maturation delay of sleep-wake mechanisms. * **First-line:** Behavioral/Lifestyle changes → Enuresis Alarm. * **Best Pharmacotherapy:** Desmopressin (oral melt formulation preferred). * **Rule Out:** Always screen for constipation, UTI, or Diabetes Mellitus if enuresis is secondary (started after a 6-month dry period).

Question 107: What is the most common cause of urinary ascites?

A. Posterior urethral valve (Correct Answer)
B. Bilateral pelviureteric junction obstruction
C. Meatal stenosis
D. Infantile polycystic kidney disease

Explanation: **Explanation:** **Urinary ascites** in a neonate is a rare but classic presentation of obstructive uropathy. **Why Posterior Urethral Valve (PUV) is the correct answer:** PUV is the most common cause of bladder outlet obstruction in male infants. The high intravesical pressure caused by the valves leads to back-pressure changes throughout the urinary tract. This pressure often results in the rupture of the renal fornix (the weakest point of the collecting system), leading to the extravasation of urine into the retroperitoneum and subsequently into the peritoneal cavity. This "pop-off mechanism" (Forniceal rupture) actually serves as a protective measure for the renal parenchyma by decompressing the system. **Analysis of Incorrect Options:** * **B. Bilateral Pelviureteric Junction (PUJ) Obstruction:** While PUJ obstruction is a common cause of neonatal hydronephrosis, it is usually unilateral. Even when bilateral, it rarely generates the extreme pressures required to cause a spontaneous rupture leading to ascites. * **C. Meatal Stenosis:** This is a distal obstruction typically seen in circumcised boys. It causes a narrow urinary stream but rarely leads to the severe proximal pressure changes or forniceal rupture seen in PUV. * **D. Infantile Polycystic Kidney Disease (ARPKD):** This is a genetic condition characterized by cystic dilatation of collecting ducts and hepatic fibrosis. It causes bilateral nephromegaly but does not involve an obstructive process that would lead to urinary extravasation. **Clinical Pearls for NEET-PG:** * **Classic Triad of PUV:** Palpable distended bladder, weak urinary stream, and bilateral hydronephrosis. * **Diagnosis:** The gold standard investigation is **Voiding Cystourethrogram (VCUG)**, which shows a dilated posterior urethra and a "spinning top" appearance. * **Initial Management:** Immediate bladder decompression using a feeding tube or catheter. * **Key Association:** Urinary ascites in a male neonate is **PUV** until proven otherwise.

Question 108: During the physical examination of a newborn boy, the pediatrician notices that the urethral meatus is positioned on the lower side of the penile shaft. What is the appropriate diagnosis for this congenital birth defect?

A. Epispadias
B. Hydroureter
C. Hypospadias (Correct Answer)
D. Peyronie disease

Explanation: ### Explanation **Correct Answer: C. Hypospadias** **Understanding the Concept:** Hypospadias is a common congenital anomaly where the **urethral meatus** is located on the **ventral (underside)** aspect of the penis, rather than at the tip of the glans. It results from the failure of the urethral folds to fuse completely during the 8th to 14th weeks of gestation. It is frequently associated with **chordee** (ventral curvature of the penis) and a "hooded" prepuce (incomplete foreskin). **Analysis of Incorrect Options:** * **A. Epispadias:** This is a rarer condition where the urethral opening is on the **dorsal (upper)** surface of the penis. It is often associated with bladder exstrophy. * **B. Hydroureter:** This refers to the dilation of the ureter, usually due to an obstruction or vesicoureteral reflux (VUR). It is an internal anatomical finding, not a visible external urethral defect. * **D. Peyronie disease:** This is an **acquired** condition in adults characterized by fibrous plaque formation in the tunica albuginea, leading to painful erections and penile curvature. It is not a congenital urethral malformation. **High-Yield Clinical Pearls for NEET-PG:** * **Management Rule:** **Circumcision is strictly contraindicated** in newborns with hypospadias because the preputial skin is required for future surgical reconstruction (urethroplasty). * **Timing of Surgery:** Ideally performed between **6 to 12 months** of age. * **Associated Findings:** Always check for **undescended testes** (cryptorchidism) and inguinal hernias. If hypospadias is severe (proximal) and associated with undescended testes, consider an evaluation for **Disorders of Sex Development (DSD)**. * **Location:** Can be glandular (most common), coronal, penile, or scrotal.

Question 109: An 8-year-old boy presents with a history of diarrhea followed by decreased urine output. Blood examination shows 90,000 thrombocytes/cm³. What is the most likely diagnosis?

A. Hemolytic Uremic Syndrome (Correct Answer)
B. Disseminated Intravascular Coagulation
C. Hemophilia
D. Idiopathic Thrombocytopenic Purpura

Explanation: ### Explanation The clinical presentation of an 8-year-old boy with a prodrome of **diarrhea**, followed by **decreased urine output** (acute kidney injury) and **thrombocytopenia** (90,000/cm³), is the classic triad of **Hemolytic Uremic Syndrome (HUS)**. #### Why Option A is Correct: HUS is the most common cause of acute renal failure in children. It typically follows an infection with Shiga toxin-producing *E. coli* (STEC), most commonly serotype **O157:H7**. The toxin causes endothelial damage, leading to microangiopathic hemolytic anemia (MAHA), thrombocytopenia (due to platelet consumption), and renal microthrombi resulting in oliguria. #### Why Other Options are Incorrect: * **B. Disseminated Intravascular Coagulation (DIC):** While DIC also presents with thrombocytopenia and renal failure, it is characterized by abnormal coagulation profiles (prolonged PT/aPTT and low fibrinogen). In HUS, the coagulation profile is typically **normal**. * **C. Hemophilia:** This is an X-linked recessive disorder causing factor VIII or IX deficiency. It presents with deep tissue bleeds or hemarthrosis, not diarrhea-associated renal failure or thrombocytopenia. * **D. Idiopathic Thrombocytopenic Purpura (ITP):** ITP presents with isolated thrombocytopenia, usually following a viral respiratory infection. It does not cause renal failure or follow a diarrheal prodrome. #### High-Yield Clinical Pearls for NEET-PG: * **The HUS Triad:** 1. Microangiopathic Hemolytic Anemia (Schistocytes on smear), 2. Thrombocytopenia, 3. Acute Kidney Injury. * **Management:** Primarily supportive (fluid/electrolyte balance, dialysis). **Antibiotics and anti-motility agents are contraindicated** as they may increase toxin release and worsen the condition. * **Atypical HUS:** Caused by uncontrolled complement activation (Factor H deficiency); it does not require a diarrheal prodrome.

Question 110: An infant with a history of diarrhea 5 days back presents with urea of 200 mg% and creatinine of 5 mg/dL. The platelet count is 90,000/mm 3. Fragmented RBCs are found in the peripheral smear. What is the most likely diagnosis?

A. Hemolytic Uremic Syndrome (HUS) (Correct Answer)
B. Thrombotic Thrombocytopenic Purpura (TTP)
C. Idiopathic Thrombocytopenic Purpura (ITP)
D. Hemolytic Anemia

Explanation: ### Explanation The clinical presentation describes the classic **triad of Hemolytic Uremic Syndrome (HUS)**: 1. **Microangiopathic Hemolytic Anemia (MAHA):** Evidence of fragmented RBCs (schistocytes) on peripheral smear. 2. **Thrombocytopenia:** Platelet count <150,000/mm³ (90,000 in this case). 3. **Acute Kidney Injury (AKI):** Significantly elevated Urea (200 mg%) and Creatinine (5 mg/dL). The history of **diarrhea** 5 days prior strongly suggests **Typical HUS**, usually caused by Shiga toxin-producing *E. coli* (STEC, O157:H7). The toxin damages glomerular endothelial cells, leading to microthrombi formation, which consumes platelets and mechanically shears RBCs. #### Why the other options are incorrect: * **Thrombotic Thrombocytopenic Purpura (TTP):** While it shares the MAHA and thrombocytopenia features, TTP is rare in infants and typically presents with a **pentad** including prominent neurological symptoms and fever. It is caused by ADAMTS13 deficiency. * **Idiopathic Thrombocytopenic Purpura (ITP):** ITP presents with isolated thrombocytopenia. It does **not** cause fragmented RBCs (hemolysis) or renal failure. * **Hemolytic Anemia:** This is a broad term. While hemolysis is present here, it does not account for the concurrent thrombocytopenia and acute renal failure. #### NEET-PG High-Yield Pearls: * **Most common cause of AKI in children:** HUS. * **Typical HUS:** Preceded by bloody diarrhea (*E. coli* O157:H7); prognosis is generally good with supportive care. * **Atypical HUS:** Due to alternative complement pathway dysregulation; carries a poorer prognosis and requires Eculizumab. * **Management:** Primarily supportive (fluids, dialysis). **Antibiotics and anti-motility agents are contraindicated** in STEC-HUS as they may increase toxin release.

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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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