Nephrology Practice Questions

Q: A 12-year-old boy presents with gross hematuria and elevated serum immunoglobulin A. Two days prior, he experienced a mild upper respiratory tract infection. What is the most likely diagnosis?

IgA Nephropathy. ### Explanation **Correct Answer: B. IgA Nephropathy (Berger’s Disease)** The clinical presentation is classic for **IgA Nephropathy**, the most common cause of primary glomerulonephritis worldwide. The hallmark is **synpharyngitic hematuria**—gross hematuria occurring simultaneously with or within 1–2 days of an upper respiratory tract infection (URTI). This occurs because mucosal infections trigger the production of galactose-deficient IgA1, which forms immune complexes that deposit in the glomerular mesangium. Elevated serum IgA levels are seen in about 50% of cases. **Why other options are incorrect:** * **Post-streptococcal glomerulonephritis (PSGN):** This typically presents with a longer latent period (1–3 weeks) after a sore throat or skin infection. It is associated with low C3 complement levels, whereas IgA nephropathy usually has normal complement levels. * **Henoch-Schönlein Purpura (HSP):** While HSP shares the same pathology (IgA deposition), it is a systemic vasculitis. Diagnosis requires systemic features like palpable purpura (usually on lower limbs), abdominal pain, and arthritis, which are absent here. * **Microangiopathic Hemolytic Anemia (MAHA):** This is a feature of Hemolytic Uremic Syndrome (HUS), characterized by the triad of microangiopathic anemia, thrombocytopenia, and acute kidney injury, usually following bloody diarrhea. **High-Yield Clinical Pearls for NEET-PG:** * **Latent Period:** IgA Nephropathy (<3 days) vs. PSGN (1–3 weeks). * **Complement Levels:** Normal in IgA Nephropathy; Low (C3) in PSGN. * **Prognosis:** The most common indicator of poor prognosis in IgA Nephropathy is persistent proteinuria. * **Association:** IgA Nephropathy is considered a renal-limited version of HSP.

Q: What is the drug of choice for steroid-resistant nephrotic syndrome?

Tacrolimus. **Explanation:** The management of Nephrotic Syndrome in children is categorized based on the response to corticosteroids. **Steroid-Resistant Nephrotic Syndrome (SRNS)** is defined as the failure to achieve remission after 4 weeks of daily therapy with prednisolone (2 mg/kg/day). **Why Tacrolimus is the Correct Answer:** According to the latest Indian Society of Pediatric Nephrology (ISPN) guidelines, **Calcineurin Inhibitors (CNIs)** are the first-line treatment for SRNS. **Tacrolimus** is preferred over Cyclosporine due to its superior efficacy in inducing remission and a more favorable side-effect profile (lower risk of hirsutism and gingival hyperplasia). It works by inhibiting T-cell activation and stabilizing the podocyte cytoskeleton. **Analysis of Incorrect Options:** * **A. Cyclophosphamide:** While used in Steroid-Dependent or Frequently Relapsing Nephrotic Syndrome (SDNS/FRNS), it has a very low efficacy rate in SRNS and is not the drug of choice. * **B. Mycophenolate Mofetil (MMF):** MMF is primarily used as a steroid-sparing agent in SDNS or as maintenance therapy in SRNS after remission is induced by CNIs. It is generally less effective than Tacrolimus for initial induction in SRNS. * **C. Prednisolone:** This is the drug of choice for the *first episode* of Nephrotic Syndrome. By definition, SRNS has already failed to respond to this medication. **High-Yield Clinical Pearls for NEET-PG:** * **Most common histological finding in SRNS:** Focal Segmental Glomerulosclerosis (FSGS). * **Genetic Testing:** Recommended in children with SRNS, especially those under 1 year of age (Congenital Nephrotic Syndrome), as they are unlikely to respond to immunosuppression. * **Side Effects of Tacrolimus:** Nephrotoxicity (monitor trough levels), New-Onset Diabetes After Transplantation (NODAT), and tremors.

Q: A 12-year-old boy is referred for evaluation of nocturnal enuresis and short stature. His blood pressure is normal. Laboratory investigations reveal: blood urea 112 mg/dl, creatinine 6 mg/dl, sodium 119 mEq/l, potassium 4 mEq/l, calcium 7 mg/dl, phosphate 6 mg/dl, and alkaline phosphatase 400 U/l. Urinalysis shows trace proteinuria with hyaline casts; no red or white cells are seen. Ultrasound shows bilateral small kidneys, and the micturating cystourethrogram is normal. What is the most likely diagnosis?

Nephronophthisis. **Explanation:** The clinical presentation of a child with **short stature, nocturnal enuresis (polyuria), and progressive renal failure** with small, echogenic kidneys is classic for **Nephronophthisis (NPHP)**. **Why Nephronophthisis is the correct answer:** 1. **Clinical Triad:** It typically presents in late childhood with a defect in urinary concentration (polyuria/polydipsia), leading to nocturnal enuresis. 2. **Renal Failure:** The lab values (Creatinine 6 mg/dl, Urea 112 mg/dl) indicate End-Stage Renal Disease (ESRD). 3. **Salt-Wasting:** The low sodium (119 mEq/l) is a hallmark of NPHP, as it is a "salt-wasting" nephropathy due to tubular dysfunction. 4. **Imaging:** Ultrasound shows small, shrunken kidneys (unlike many other pediatric renal diseases), and the absence of hematuria/significant proteinuria points toward a tubulointerstitial process rather than glomerular disease. **Why other options are incorrect:** * **Alport’s Syndrome:** Characterized by persistent microscopic hematuria, sensorineural deafness, and ocular defects. The urinalysis here is bland (no RBCs). * **Medullary Sponge Kidney:** Usually asymptomatic in childhood or presents with nephrolithiasis and hematuria. It does not typically lead to early ESRD or small kidneys. * **Chronic Glomerulonephritis:** Usually presents with significant proteinuria, hematuria, and **hypertension**. This patient has normal blood pressure and minimal proteinuria. **High-Yield Clinical Pearls for NEET-PG:** * **Nephronophthisis** is the most common genetic cause of ESRD in children and adolescents. * It is an **Autosomal Recessive** ciliopathy. * **Key Triad:** Polyuria, Growth Retardation, and Anemia out of proportion to renal failure. * **Associated Syndromes:** Senior-Løken syndrome (NPHP + Retinitis Pigmentosa) and Joubert syndrome (NPHP + Cerebellar ataxia).

Q: What is the most common gene defect in idiopathic steroid-resistant nephrotic syndrome?

NPHS 2. ### Explanation **Correct Option: B. NPHS 2** Steroid-resistant nephrotic syndrome (SRNS) is frequently caused by genetic mutations affecting the structural integrity of the glomerular filtration barrier, specifically the podocyte. * **NPHS 2** encodes the protein **Podocin**. Mutations in this gene are the **most common genetic cause** of idiopathic SRNS in both children and adults. It typically presents as Focal Segmental Glomerulosclerosis (FSGS) on biopsy and does not respond to corticosteroid therapy. **Incorrect Options:** * **A. ACE (Angiotensin-Converting Enzyme):** While ACE inhibitors are used to reduce proteinuria in chronic kidney disease, mutations in the ACE gene are not a primary cause of SRNS. * **C. HOX 11:** This gene is involved in spleen development and T-cell leukemia; it has no established role in the pathogenesis of nephrotic syndrome. * **D. PAX (e.g., PAX2):** Mutations in PAX2 are associated with **Renal-Coloboma Syndrome** (optic nerve coloboma and renal hypoplasia/dysplasia), not typically idiopathic SRNS. **High-Yield Clinical Pearls for NEET-PG:** * **NPHS 1:** Encodes **Nephrin**. Mutations cause **Congenital Nephrotic Syndrome of the Finnish type** (presents within the first 3 months of life). * **NPHS 2:** Encodes **Podocin**. Most common cause of familial/idiopathic SRNS. * **WT1 Mutation:** Associated with **Denys-Drash Syndrome** (nephropathy, Wilms tumor, and pseudohermaphroditism). * **Management Note:** Genetic SRNS generally does not respond to immunosuppressants, and the risk of recurrence after kidney transplantation is lower compared to non-genetic cases.

Q: Infants with hypernatraemic dehydration present with all of the following except?

Depressed anterior fontanelle. In hypernatremic dehydration (Serum Sodium >150 mEq/L), water shifts from the intracellular space to the extracellular space (ECF) to maintain osmotic balance. This shift **preserves the intravascular and interstitial volumes** at the expense of intracellular fluid. ### Why "Depressed Anterior Fontanelle" is the Correct Answer: In typical isonatremic or hyponatremic dehydration, the loss of ECF leads to classic physical signs like a depressed anterior fontanelle, poor skin turgor (tenting), and sunken eyes. However, in **hypernatremic dehydration**, the ECF volume is relatively well-maintained. Consequently, the skin often feels **doughy or velvety** rather than losing turgor, and the fontanelle may remain flat or only slightly depressed, making it a misleading sign. ### Explanation of Incorrect Options: * **Dry Tongue:** This is a common feature of all types of dehydration due to decreased salivary secretions and mucosal dryness. * **Altered Consciousness:** This is a hallmark of hypernatremia. The shrinkage of brain cells (intracellular dehydration) leads to irritability, high-pitched crying, lethargy, seizures, or even coma. * **Thready, Feeble Pulse:** While circulatory collapse occurs later in hypernatremia compared to other types, severe dehydration will eventually lead to tachycardia and a thready pulse as compensatory mechanisms fail. ### NEET-PG High-Yield Pearls: 1. **The "Doughy" Feel:** The most characteristic skin finding in hypernatremic dehydration is a **doughy or rubbery texture**. 2. **Neurological Risk:** Rapid correction of hypernatremia can lead to **Cerebral Edema**. The goal is to lower sodium by no more than **0.5 mEq/L per hour** (or 10-12 mEq/L in 24 hours). 3. **Most Common Cause:** In infants, it is often due to improper dilution of formula or severe osmotic diarrhea.

Q: Convulsions in a child with dehydration and vomiting can only be due to:

Decreased serum sodium. In a child presenting with dehydration and vomiting, the most likely electrolyte imbalance leading to convulsions is **Hyponatremia (Decreased serum sodium).** ### **Why the Correct Answer is Right** Vomiting leads to the loss of both water and electrolytes. If the child is rehydrated with plain water or low-solute fluids (hypotonic rehydration), the extracellular fluid becomes dilute. This creates an osmotic gradient that shifts water into the brain cells, leading to **cerebral edema**. This increased intracranial pressure and neuronal irritability manifest clinically as seizures. Additionally, severe hyponatremia (<120 mEq/L) directly lowers the seizure threshold. ### **Why the Other Options are Incorrect** * **Decreased serum magnesium (Hypomagnesemia):** While it can cause seizures (often associated with hypocalcemia), it is rarely a direct consequence of simple dehydration and vomiting. It is more common in malabsorption syndromes or specific renal losses. * **Decreased serum potassium (Hypokalemia):** Vomiting typically causes hypokalemia, but this manifests as **muscle weakness, paralytic ileus, and ECG changes** (U waves, flattened T waves). It does not typically cause convulsions. * **Decreased serum calcium (Hypocalcemia):** While it causes tetany and seizures, it is not a standard feature of acute dehydration. It is more common in Vitamin D deficiency or hypoparathyroidism. ### **NEET-PG High-Yield Pearls** * **Hypernatremic Dehydration:** Seizures can also occur during the *correction* of hypernatremia if the sodium level is lowered too rapidly (>0.5 mEq/L per hour), leading to cerebral edema. * **Management:** For symptomatic hyponatremic seizures, the treatment of choice is **3% Hypertonic Saline**. * **Vomiting & Acid-Base:** The classic metabolic derangement in vomiting is **Metabolic Alkalosis with Paradoxical Aciduria.**

Q: What is the most reliable method for obtaining a urine specimen?

Suprapubic aspiration. **Explanation:** In pediatric nephrology, the "gold standard" for obtaining a sterile urine specimen is **Suprapubic Aspiration (SPA)**. **1. Why Suprapubic Aspiration is the Correct Answer:** SPA involves the direct needle aspiration of urine from the bladder through the abdominal wall. Because the needle bypasses the urethra and the perineum—areas heavily colonized with commensal flora—any bacterial growth obtained via SPA is considered clinically significant (even if the colony count is <10³ CFU/mL). It is the most reliable method because it carries the lowest risk of contamination. **2. Analysis of Incorrect Options:** * **Urethral Catheterization:** While more reliable than a voided sample, it still carries a risk of introducing bacteria from the distal urethra into the specimen, leading to potential false positives. * **Midstream Voiding:** This is the standard for toilet-trained children but is highly susceptible to contamination from skin and preputial flora. In non-toilet-trained infants, "bag specimens" are notorious for high false-positive rates (up to 70%). * **Catheter Aspiration:** This typically refers to taking a sample from an indwelling catheter, which is discouraged due to the rapid formation of biofilms and high colonization rates. **3. NEET-PG High-Yield Pearls:** * **Gold Standard:** SPA is the most accurate method for diagnosing UTI in neonates and young infants. * **Diagnostic Threshold:** For SPA, **any** number of gram-negative bacilli or >several hundred gram-positive cocci is diagnostic of a UTI. * **Clinical Practice:** While SPA is the most reliable, **Urethral Catheterization** is the most common "sterile" method used in emergency departments due to its higher success rate compared to SPA (which requires a full bladder). * **Bag Collection:** Never use a bag specimen for a urine *culture*; it is only useful for *screening* (if the urinalysis is negative, it helps rule out UTI).

Question 1

Which of the following statements is true regarding primary grade IV-V vesicoureteric reflux in young children?

Accepted Answer

Postnatal scarring may occur even in the absence of urinary tract infections.

Answer

Renal scarring typically begins in the midpolar regions.

Answer

The long-term outcome is comparable in patients treated with either antibiotic prophylaxis or surgery.

Answer

Oral amoxicillin is the preferred antibiotic for prophylaxis.

Question 2

A 12-year-old boy presents with gross hematuria and elevated serum immunoglobulin A. Two days prior, he experienced a mild upper respiratory tract infection. What is the most likely diagnosis?

Accepted Answer

IgA Nephropathy

Answer

Microangiopathic hemolytic anemia

Answer

Post-streptococcal glomerulonephritis (PSGN)

Answer

Henoch-Schonlein purpura (HSP)

Question 3

What is the drug of choice for steroid-resistant nephrotic syndrome?

Accepted Answer

Tacrolimus

Answer

Cyclophosphamide

Answer

Mycophenolate mofetil

Answer

Prednisolone

Question 4

Which of the following symptoms and signs are seen in hypernatremic dehydration?

Accepted Answer

Irritability and Lethargy

Answer

Irritability and Drowsiness

Answer

Irritability and Oliguria

Answer

Lethargy and Oliguria

Question 5

A 12-year-old boy is referred for evaluation of nocturnal enuresis and short stature. His blood pressure is normal. Laboratory investigations reveal: blood urea 112 mg/dl, creatinine 6 mg/dl, sodium 119 mEq/l, potassium 4 mEq/l, calcium 7 mg/dl, phosphate 6 mg/dl, and alkaline phosphatase 400 U/l. Urinalysis shows trace proteinuria with hyaline casts; no red or white cells are seen. Ultrasound shows bilateral small kidneys, and the micturating cystourethrogram is normal. What is the most likely diagnosis?

Accepted Answer

Nephronophthisis

Answer

Alport's syndrome

Answer

Medullary sponge kidney

Answer

Chronic glomerulonephritis

Question 6

What is the most common gene defect in idiopathic steroid-resistant nephrotic syndrome?

Accepted Answer

NPHS 2

Answer

ACE

Answer

HOX 11

Answer

PAX

Question 7

Infants with hypernatraemic dehydration present with all of the following except?

Accepted Answer

Depressed anterior fontanelle

Answer

Dry tongue

Answer

Altered consciousness

Answer

Thready, feeble pulse

Question 8

Convulsions in a child with dehydration and vomiting can only be due to:

Accepted Answer

Decreased serum sodium

Answer

Decreased serum magnesium

Answer

Decreased serum potassium

Answer

Decreased serum calcium

Question 9

A child has deficient bone mineralization with low serum calcium, high serum phosphorus, with decreased urinary excretion of calcium and phosphorus, and elevated levels of alkaline phosphatase. What is the most likely diagnosis?

Accepted Answer

Renal glomerular rickets

Answer

Nutritional rickets

Answer

Renal tubular rickets

Answer

Celiac rickets

Question 10

What is the most reliable method for obtaining a urine specimen?

Accepted Answer

Suprapubic aspiration

Answer

Urethral catheterization

Answer

Catheter aspiration

Answer

Midstream voiding

Nephrology — MCQs

Nephrology — MCQs

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