Nephrology Practice Questions

Q: A 3-year-old child presented with a history of abdominal mass, polyuria, and polydipsia. Investigations, including intravenous pyelography, revealed a streaky appearance of the kidneys. What is the chromosomal location of the gene involved in this condition?

6p. ### Explanation The clinical presentation described—a 3-year-old with an abdominal mass, polyuria, polydipsia, and a characteristic **"streaky appearance"** on intravenous pyelography (IVP)—is classic for **Autosomal Recessive Polycystic Kidney Disease (ARPKD)**. **1. Why 6p is Correct:** ARPKD is caused by a mutation in the **PKHD1 gene**, which is located on the **short arm of chromosome 6 (6p)**. This gene encodes **fibrocystin** (also known as polyductin), a protein found in the primary cilia of epithelial cells in the renal tubules and bile ducts. In ARPKD, the kidneys undergo fusiform dilation of the collecting ducts. On IVP, the contrast fills these dilated ducts, creating the pathognomonic **"sunburst" or "streaky" appearance**. Polyuria and polydipsia occur due to a defect in the concentrating ability of the distal tubules. **2. Why Other Options are Incorrect:** * **6q:** While the gene is on chromosome 6, it is specifically located on the short arm (p), not the long arm (q). * **14p/14q:** These locations are not associated with ARPKD. However, mutations in **PKD1** (Chromosome **16p**) and **PKD2** (Chromosome **4q**) are responsible for Autosomal Dominant Polycystic Kidney Disease (ADPKD), which typically presents in adulthood. **3. Clinical Pearls for NEET-PG:** * **Hepatic Involvement:** ARPKD is universally associated with **Congenital Hepatic Fibrosis**. If the patient survives the neonatal period, they often develop portal hypertension and splenomegaly. * **Potter Sequence:** Severe cases present at birth with pulmonary hypoplasia, limb deformities, and characteristic facies due to oligohydramnios. * **Ultrasound Finding:** Bilateral, symmetrically enlarged, echogenic ("bright") kidneys with loss of corticomedullary differentiation. * **Differential:** Unlike ADPKD, the cysts in ARPKD are microscopic and represent dilated collecting ducts, not discrete macrocysts.

Q: What is the most common cause of severe obstructive uropathy in neonates?

Posterior urethral valves. **Explanation:** **Posterior Urethral Valves (PUV)** is the most common cause of lower urinary tract obstruction (LUTO) in male neonates and the leading cause of severe obstructive uropathy in the neonatal period. It occurs due to the presence of abnormal congenital mucosal folds in the prostatic urethra, which act as a valve, impeding the outflow of urine from the bladder. * **Why Option C is correct:** PUV leads to high-pressure urinary retention, causing secondary bladder wall hypertrophy, bilateral hydroureteronephrosis, and potentially irreversible renal dysplasia. It is a frequent cause of chronic kidney disease (CKD) in children. * **Why Option A is incorrect:** Prune-Belly syndrome (Eagle-Barrett syndrome) is a rare triad of abdominal muscle deficiency, undescended testes, and urinary tract abnormalities. While it involves uropathy, it is significantly less common than PUV. * **Why Option B is incorrect:** Bladder neck obstruction is a rare cause of neonatal uropathy and is usually a diagnosis of exclusion or associated with neurogenic bladder rather than a primary obstructive anatomical entity like PUV. **High-Yield Clinical Pearls for NEET-PG:** 1. **Antenatal Presentation:** Often detected on ultrasound as bilateral hydronephrosis, a distended thick-walled bladder, and the characteristic **"Keyhole sign"** (dilated posterior urethra). 2. **Clinical Sign:** A neonate with a **poor/dribbling urinary stream** and a palpable midline abdominal mass (distended bladder). 3. **Gold Standard Investigation:** **Voiding Cystourethrogram (VCUG)** is the definitive diagnostic test. 4. **Immediate Management:** Bladder drainage via a feeding tube/catheter, followed by definitive surgical management (Endoscopic Valve Ablation).

Q: What is the most common cause of end-stage renal disease (ESRD) in children?

Nephronophthisis. **Explanation:** **Nephronophthisis (NPHP)** is the most common genetic cause of end-stage renal disease (ESRD) in children and adolescents. It is an autosomal recessive tubulointerstitial cystic kidney disease. Unlike adult-onset renal failure, which is often driven by glomerular diseases or diabetes, pediatric ESRD is frequently caused by **ciliopathies** and congenital anomalies of the kidney and urinary tract (CAKUT). NPHP typically presents with a triad of polyuria, polydipsia, and anemia, leading to progressive renal failure by the first or second decade of life. **Analysis of Options:** * **Nephronophthisis (Correct):** It is the leading inherited cause of pediatric ESRD. On ultrasound, kidneys appear normal-sized or small with increased echogenicity and loss of corticomedullary differentiation; cysts are usually small and located at the corticomedullary junction. * **ADPKD (Incorrect):** While it is the most common inherited kidney disease overall, it typically manifests in **adulthood** (4th–5th decade). It rarely causes ESRD during childhood. * **Medullary Cystic Disease (Incorrect):** Now often referred to as Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD), it is clinically similar to NPHP but presents in **adults** (mean age of ESRD is 30–50 years). * **ARPKD (Incorrect):** Although it presents in infancy or childhood with massive bilateral kidney enlargement, it is statistically less common as a cause of ESRD compared to the NPHP group of disorders. **Clinical Pearls for NEET-PG:** * **Key Triad:** Polyuria, Polydipsia, and Anemia (due to early erythropoietin deficiency) in a child with a "bland" urine sediment (no blood/protein). * **Senior-Løken Syndrome:** NPHP associated with Retinitis Pigmentosa (High-yield association). * **Imaging:** Unlike polycystic diseases, NPHP usually features **small to normal-sized kidneys.**

Q: A 7-year-old girl presents with generalized body swelling. Urinalysis shows grade 3 proteinuria and the presence of hyaline and fatty casts. She has no history of hematuria. Which of the following statements about her condition is true?

No IgG deposits or C3 deposition on renal biopsy. The clinical presentation of generalized body swelling (edema) and heavy proteinuria (Grade 3) in a 7-year-old child, in the absence of hematuria, is the classic hallmark of **Minimal Change Disease (MCD)**. MCD is the most common cause of Nephrotic Syndrome in children (approx. 80% of cases). ### **Why Option A is Correct** In Minimal Change Disease, **Immunofluorescence (IF) microscopy** typically shows **no deposits** (negative for IgG, IgA, IgM, and C3). The primary pathology is seen only on Electron Microscopy, which reveals the **effacement (fusion) of podocyte foot processes**. Light microscopy usually appears normal, hence the name "Minimal Change." ### **Why Other Options are Incorrect** * **Option B (Low C3):** MCD is characterized by normal serum complement levels. Low C3 levels are seen in "nephritic" conditions like Post-Streptococcal Glomerulonephritis (PSGN), Membranoproliferative Glomerulonephritis (MPGN), or Systemic Lupus Erythematosus (SLE). * **Option C (IgA Nephropathy):** This typically presents as asymptomatic microscopic hematuria or gross hematuria following an upper respiratory tract infection (synpharyngitic hematuria), not pure nephrotic syndrome. * **Option D (Alport’s Syndrome):** This is a hereditary collagen disorder presenting with hematuria, progressive renal failure, sensorineural hearing loss, and ocular defects (lenticonus). ### **High-Yield NEET-PG Pearls** * **Most common cause of Nephrotic Syndrome in children:** Minimal Change Disease. * **Most common cause in adults:** Focal Segmental Glomerulosclerosis (FSGS) or Membranous Nephropathy. * **Hallmark finding:** Effacement of foot processes on Electron Microscopy. * **Treatment of choice:** Corticosteroids (Prednisolone). MCD is highly steroid-responsive. * **Selectivity:** Proteinuria in MCD is typically "highly selective" (mainly albumin).

Q: In children, what is the definition of acute kidney injury in terms of urine output?

Less than 0.5 ml/kg/hr for more than 6 hours. The definition of Acute Kidney Injury (AKI) in children is primarily based on the **pRIFLE** (Pediatric Risk, Injury, Failure, Loss, End-stage renal disease) and **KDIGO** criteria. Both classifications define the earliest stage of AKI (Stage 1 or "Risk") based on a reduction in urine output. ### Why Option B is Correct The standard pediatric threshold for AKI is a urine output of ** 1 ml/kg/hr) and serves as an early physiological marker of declining glomerular filtration before a significant rise in serum creatinine occurs. ### Analysis of Incorrect Options * **Option A ( 12 hours, or **Stage 3 (Failure)** if it persists for >24 hours. It is too stringent for the initial definition of AKI. * **Options C & D:** These values are too high. While a child producing 0.8 or 1 ml/kg/hr may be monitored, they do not meet the formal diagnostic criteria for AKI. ### High-Yield Clinical Pearls for NEET-PG * **Creatinine Criteria:** In children, AKI is also defined as an increase in serum creatinine to **≥1.5 times the baseline** or an absolute increase of **≥0.3 mg/dL** within 48 hours. * **pRIFLE vs. KDIGO:** While KDIGO is the global standard, **pRIFLE** is specifically validated for pediatrics and uses "estimated Creatinine Clearance (eCCl)" rather than absolute creatinine values. * **Normal Urine Output:** * Infants: 2 ml/kg/hr * Children: 1–1.5 ml/kg/hr * Adolescents: 0.5–1 ml/kg/hr

Question 1

A 3-year-old child presented with a history of abdominal mass, polyuria, and polydipsia. Investigations, including intravenous pyelography, revealed a streaky appearance of the kidneys. What is the chromosomal location of the gene involved in this condition?

Accepted Answer

6p

Answer

6q

Answer

14p

Answer

14q

Question 2

What is the most common cause of severe obstructive uropathy in neonates?

Accepted Answer

Posterior urethral valves

Answer

Prune-Belly syndrome

Answer

Bladder neck obstruction

Answer

None of these

Question 3

A six-month-old girl presents with recurrent urinary tract infections. Ultrasound of the abdomen reveals bilateral hydronephrosis. A micturating cystourethrogram (MCU) demonstrates bilateral Grade IV vesicoureteral reflux. What is the initial treatment of choice?

Accepted Answer

Prophylactic antibiotics

Answer

Endoscopic injection of Deflux at the ureteral orifices

Answer

Ureteral reimplantation

Answer

Bilateral ureterostomy

Question 4

What is the most common cause of end-stage renal disease (ESRD) in children?

Accepted Answer

Nephronophthisis

Answer

Autosomal dominant polycystic kidney disease (ADPKD)

Answer

Medullary cystic disease

Answer

Autosomal recessive polycystic kidney disease (ARPKD)

Question 5

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

Accepted Answer

Diuretic therapy

Answer

Adrenal tumor

Answer

Thiazide therapy

Answer

Diarrhea

Question 6

All are features of hemolytic uremic syndrome, except?

Accepted Answer

Neuropsychiatric disturbances

Answer

Hyperkalemia

Answer

Anemia

Answer

Renal microthrombi

Question 7

An 11-year-old child presents with failure to thrive and metabolic acidosis with an increased anion gap. Which of the following is NOT a likely diagnosis in the differential diagnosis?

Accepted Answer

Renal tubular acidosis

Answer

Insulin dependent diabetes mellitus

Answer

Chronic renal failure

Answer

Inborn errors of metabolism

Question 8

A 5-year-old girl, without a past history of UTI, is in the hospital receiving antibiotics for E coli pyelonephritis. She remains febrile after 4 days of appropriate antibiotic treatment. A renal ultrasound shows no abscess, but a focal enlargement of one of the lobes of the right kidney. A CT scan of the abdomen reveals a wedge-shaped area in the right kidney distinct from the normal tissue with minimal contrast enhancement. What is the appropriate management for this patient?

Accepted Answer

Prolonged antibiotic therapy

Answer

Routine treatment with 10 to 14 days of antibiotics for pyelonephritis

Answer

Surgical consultation

Answer

Dimercaptosuccinic acid (DMSA) scan

Question 9

A 7-year-old girl presents with generalized body swelling. Urinalysis shows grade 3 proteinuria and the presence of hyaline and fatty casts. She has no history of hematuria. Which of the following statements about her condition is true?

Accepted Answer

No IgG deposits or C3 deposition on renal biopsy

Answer

C3 level will be low

Answer

IgA nephropathy is the likely diagnosis

Answer

Alport's syndrome is the likely diagnosis

Question 10

In children, what is the definition of acute kidney injury in terms of urine output?

Accepted Answer

Less than 0.5 ml/kg/hr for more than 6 hours

Answer

Less than 0.3 ml/kg/hr for more than 6 hours

Answer

Less than 0.8 ml/kg/hr for more than 6 hours

Answer

Less than 1 ml/kg/hr for more than 6 hours

Nephrology — MCQs

Nephrology — MCQs

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