Nephrology Practice Questions

Q: Which of the following is a characteristic feature of Henoch-Schonlein purpura?

Palpable purpura. **Explanation:** **Henoch-Schönlein Purpura (HSP)**, now commonly referred to as **IgA Vasculitis**, is the most common systemic small-vessel vasculitis in children. It is characterized by the deposition of IgA-dominant immune complexes in the walls of small vessels (capillaries, venules, and arterioles). **Why Option B is Correct:** **Palpable purpura** is the hallmark clinical feature of HSP and is a mandatory criterion for diagnosis. Unlike simple petechiae, these lesions are elevated and "palpable" because the underlying pathology is **vasculitis** (inflammation of the vessel wall), which leads to localized edema and cellular infiltration along with the extravasation of RBCs. They typically appear in a symmetrical distribution on dependent areas like the lower limbs and buttocks. **Why Incorrect Options are Wrong:** * **Option A:** HSP primarily affects **children** (peak age 3–10 years). While it can occur in adults, it is rare in the elderly. * **Option C:** HSP is a **non-thrombocytopenic purpura**. The platelet count is characteristically **normal or even elevated** (thrombocytosis). If a patient has a low platelet count, an alternative diagnosis like Immune Thrombocytopenic Purpura (ITP) must be considered. **High-Yield Clinical Pearls for NEET-PG:** * **Classic Tetrad:** 1. Palpable purpura (without thrombocytopenia), 2. Arthritis/Arthralgia, 3. Abdominal pain (due to intramural hemorrhage), 4. Renal involvement (IgA Nephropathy). * **Trigger:** Often follows an Upper Respiratory Tract Infection (URTI). * **Complication:** The most common GI complication is **Intussusception** (typically ileo-ileal). * **Prognosis:** Generally excellent, but long-term prognosis depends entirely on the severity of **renal involvement**.

Q: What is the most devastating consequence of hypernatremic dehydration in children?

Brain hemorrhage. **Explanation:** In hypernatremic dehydration (Serum Na+ >150 mEq/L), the extracellular fluid (ECF) becomes hypertonic. To maintain osmotic equilibrium, water moves out of the intracellular space into the ECF. When this occurs in the central nervous system, the **brain cells shrink**. As the brain volume decreases, it pulls away from the meninges, putting mechanical tension on the fragile **bridging veins**. This tension leads to the rupture of these vessels, resulting in **subdural, subarachnoid, and intracerebral hemorrhages**. This is considered the most devastating consequence due to the high risk of permanent neurological deficit or death. **Analysis of Incorrect Options:** * **A. Seizures:** While common during hypernatremia (due to cellular dehydration) or during rapid rehydration (due to cerebral edema), they are usually manageable and less "devastating" than a major intracranial bleed. * **B. Hyperglycemia:** Often seen in hypernatremic dehydration due to stress-induced insulin resistance and decreased insulin secretion, but it is a metabolic association rather than a life-threatening structural consequence. * **D. Hypocalcemia:** Frequently associated with hypernatremia (mechanism unclear, possibly related to calcium entry into cells), but it is rarely the primary cause of mortality or long-term morbidity in these patients. **High-Yield Clinical Pearls for NEET-PG:** * **The "Doughy" Skin Feel:** A classic physical exam finding in hypernatremic dehydration due to the preservation of ECF volume at the expense of ICF. * **Management Rule:** Never lower Serum Na+ faster than **0.5 mEq/L/hour** (or 10–12 mEq/L per 24 hours) to prevent **Cerebral Edema**. * **Idiogenic Osmoles:** The brain produces these (e.g., taurine, sorbitol) to protect itself from shrinking during chronic hypernatremia; rapid rehydration makes these osmoles pull water into the brain too quickly.

Q: What are the diagnostic criteria for post-streptococcal glomerulonephritis in children?

Mild proteinuria, hematuria, low ASO titre. **Explanation:** Post-Streptococcal Glomerulonephritis (PSGN) is a classic **Nephritic Syndrome** occurring after a Group A Beta-hemolytic Streptococcal infection (pharyngitis or pyoderma). 1. **Why Option C is correct:** * **Hematuria:** This is the hallmark of nephritic syndrome, often presenting as "cola-colored" or smoky urine due to glomerular inflammation. * **Mild Proteinuria:** Unlike Nephrotic syndrome, PSGN typically presents with sub-nephrotic range proteinuria (<3.5g/day). * **Low Complement (C3):** While the question mentions "low ASO titre" in the key provided, it is important to note that in clinical practice, **C3 is characteristically low** in the acute phase. Regarding ASO, it is elevated in 80% of post-pharyngeal cases but may be low or absent in post-skin infections (where Anti-DNase B is more reliable). 2. **Why other options are incorrect:** * **Options A & B:** "Heavy proteinuria" and "High cholesterol" are features of **Nephrotic Syndrome** (e.g., Minimal Change Disease), not PSGN. * **Option D:** PSGN is associated with normal cholesterol levels; high cholesterol is a metabolic consequence of the protein loss seen in Nephrotic syndrome. **NEET-PG High-Yield Pearls:** * **Latent Period:** 1–2 weeks after pharyngitis; 3–6 weeks after pyoderma (impetigo). * **Most sensitive marker:** Low **C3 complement** levels (returns to normal within 6–8 weeks). If C3 remains low after 8 weeks, consider MPGN or SLE. * **Microscopy:** "Lumpy-bumpy" appearance or "Starry sky" pattern on Immunofluorescence due to IgG and C3 deposits. * **Electron Microscopy:** Pathognomonic **Sub-epithelial humps**. * **Management:** Primarily supportive (fluid restriction, diuretics for hypertension/edema). Antibiotics do not prevent the development of PSGN but limit the spread of the nephritogenic strain.

Q: What is the most common cause of renovascular hypertension in children and young adults?

Fibromuscular dysplasia. **Explanation:** Renovascular hypertension (RVH) is the most common cause of secondary hypertension in the pediatric population. It occurs due to the narrowing of one or more renal arteries, leading to the activation of the Renin-Angiotensin-Aldosterone System (RAAS). **1. Why Fibromuscular Dysplasia (FMD) is correct:** In children and young adults, **Fibromuscular Dysplasia** is the leading cause of renovascular hypertension. It is a non-inflammatory, non-atherosclerotic angiopathy that causes abnormal growth within the arterial wall. In children, the **intimal** subtype is most common, whereas the **medial** subtype (classic "string of beads" appearance) is more frequent in adults. Another significant cause in the Indian context is Takayasu Arteritis, but FMD remains the global textbook answer for this demographic. **2. Why the other options are incorrect:** * **Atherosclerotic disease:** This is the most common cause of RVH in the **elderly**, typically occurring at the ostium of the renal artery. It is rare in children. * **Ectopic kidney:** While anatomical variations can sometimes be associated with abnormal vasculature, they are not a primary cause of renovascular hypertension. * **Polycystic kidney disease (PKD):** PKD causes hypertension through intrarenal ischemia and RAAS activation due to cyst expansion, but it is classified as a **parenchymal** cause of hypertension, not a renovascular one. **High-Yield Clinical Pearls for NEET-PG:** * **Gold Standard Investigation:** Digital Subtraction Angiography (DSA). * **Initial Screening:** Doppler Ultrasonography or CT Angiography. * **Associated Syndromes:** Always screen for RVH in children with Neurofibromatosis type 1 (NF-1) or Williams syndrome. * **Bruit:** A continuous epigastric or flank bruit is a specific clinical sign of RVH.

Q: A 10-year-old child with a history of sore throat one week ago presents with sudden onset of hematuria, generalized edema, and hypertension. Laboratory findings reveal proteinuria, red blood cell casts in the urine, deranged renal function tests, and low serum complement C3 levels. What is the most likely histological finding if a kidney biopsy is performed?

Diffuse proliferative glomerulonephritis. ### Explanation The clinical presentation of hematuria (coca-cola colored urine), hypertension, edema, and low C3 levels following a sore throat (pharyngitis) is classic for **Post-Streptococcal Glomerulonephritis (PSGN)**. **1. Why Option A is Correct:** PSGN is the most common cause of acute nephritic syndrome in children. The characteristic histological finding on light microscopy is **Diffuse Proliferative Glomerulonephritis**. This is characterized by hypercellular glomeruli due to the proliferation of endothelial and mesangial cells, along with an influx of neutrophils and monocytes. On electron microscopy, pathognomonic **"subepithelial humps"** (IgG and C3 deposits) are seen. **2. Why Other Options are Incorrect:** * **B. Minimal Change Disease:** This is the most common cause of **Nephrotic Syndrome** in children. It presents with massive proteinuria and normal C3 levels. Light microscopy typically appears normal. * **C. Focal Segmental Glomerulosclerosis (FSGS):** This presents with nephrotic syndrome and is characterized by sclerosis in parts (segmental) of some (focal) glomeruli. It does not typically follow a streptococcal infection or show low C3. * **D. Membranous Nephropathy:** Common in adults, it presents with nephrotic syndrome. Histology shows diffuse thickening of the glomerular basement membrane with "spikes" on silver stain, not diffuse proliferation. **Clinical Pearls for NEET-PG:** * **Latent Period:** 1–3 weeks after pharyngitis; 3–6 weeks after skin infection (impetigo). * **Complement Levels:** Serum **C3 is low** but returns to normal within 6–8 weeks. If C3 remains low beyond 8 weeks, consider Membranoproliferative Glomerulonephritis (MPGN). * **Serology:** Anti-Streptolysin O (ASO) titer is elevated after pharyngitis; Anti-DNase B is the most sensitive marker after skin infections. * **Prognosis:** Excellent in children; >95% recover completely with supportive care.

Q: Urinary retention in a child is most commonly caused by what condition?

Meatal stricture with ulceration. **Explanation:** **Correct Option: A. Meatal stricture with ulceration** In the pediatric population, the most common cause of acute urinary retention is **meatal stricture with associated ulceration**. This condition typically occurs in circumcised male infants. The loss of the protective prepuce leads to chronic irritation of the glans and meatus by ammonia in diapers (diaper dermatitis), resulting in meatitis, ulceration, and subsequent scarring (stricture). The retention is often **functional/psychogenic** in the acute phase; the child experiences intense pain during micturition (dysuria) due to the ulcer, leading to voluntary withholding of urine and bladder overdistension. **Analysis of Incorrect Options:** * **B. Posterior Urethral Valve (PUV):** While PUV is the most common cause of *obstructive* uropathy and bladder outlet obstruction in male newborns, it usually presents with a poor urinary stream, dribbling, or a palpable bladder rather than acute, complete urinary retention. * **C. Urethral stricture:** These are relatively uncommon in children compared to adults and are usually secondary to trauma (e.g., straddle injury) or previous instrumentation. * **D. Epispadias:** This is a congenital malformation where the urethra opens on the dorsal aspect of the penis. It causes incontinence or spray, not retention. **Clinical Pearls for NEET-PG:** * **Most common cause of bladder outlet obstruction in male infants:** Posterior Urethral Valve (PUV). * **Gold standard investigation for PUV:** Voiding Cystourethrogram (VCUG) – shows a dilated posterior urethra ("shield sign"). * **Management of Meatal Stricture:** Meatotomy or meatoplasty. * **Key Presentation:** Always look for a history of circumcision followed by crying during micturition or a deflected, narrow urinary stream.

Q: Which of the following is true about a child with post-streptococcal glomerulonephritis?

Severe renal dysfunction is an indication for biopsy. **Explanation:** **Post-Streptococcal Glomerulonephritis (PSGN)** is the most common cause of acute nephritic syndrome in children, typically occurring 1–3 weeks after a pharyngeal or skin infection with Group A Beta-hemolytic Streptococcus. **Why Option C is Correct:** PSGN is generally a self-limiting condition with a favorable prognosis. A renal biopsy is **not** routinely required for diagnosis. However, atypical features necessitate a biopsy to rule out other glomerular diseases (like RPGN or SLE). Indications for biopsy include: * **Severe renal dysfunction** (Rapidly rising creatinine or AKI). * Persistent low C3 levels beyond 8 weeks. * Significant proteinuria (nephrotic range) or persistent gross hematuria. * Absence of a latent period or evidence of streptococcal infection. **Analysis of Incorrect Options:** * **Option A:** While gross hematuria usually resolves within 1–2 weeks, **microscopic hematuria** can persist for a long duration, often up to **6 months to 1 year**. * **Option B:** Increased serum triglycerides are a hallmark of **Nephrotic Syndrome**, not Nephritic Syndrome (PSGN). PSGN is characterized by the nephritic triad: Hematuria, Hypertension, and Edema. * **Option D:** PSGN is a classic example of the **alternative complement pathway** activation. Therefore, **Serum C3 is characteristically low** in >90% of patients during the acute phase, typically returning to normal within 6–8 weeks. **High-Yield Clinical Pearls for NEET-PG:** * **Most common finding:** Microscopic hematuria. * **First sign of recovery:** Diuresis and resolution of edema/hypertension. * **Best screening test:** Antistreptolysin O (ASO) titer (higher in pharyngitis) or Anti-DNase B (more sensitive for skin infections/impetigo). * **Electron Microscopy:** Characterized by subepithelial "humps" (lumpy-bump appearance).

Q: Cyclosporine in nephrotic syndrome acts by which mechanism?

Inhibiting calcineurin. **Explanation:** **Cyclosporine** is a potent immunosuppressant used in steroid-resistant or steroid-dependent nephrotic syndrome. Its primary mechanism of action is the **inhibition of calcineurin**, a calcium-dependent phosphatase. 1. **Mechanism of Action:** Cyclosporine binds to an intracellular protein called **cyclophilin**. This complex then inhibits calcineurin, preventing the dephosphorylation and activation of the **Nuclear Factor of Activated T-cells (NFAT)**. Consequently, the transcription of IL-2 and other cytokines is blocked, leading to decreased T-cell activation. 2. **Podocyte Stabilization:** Beyond immunosuppression, Cyclosporine has a direct non-immunological effect on the kidney. It stabilizes the **actin cytoskeleton of podocytes** by preventing the calcineurin-mediated degradation of **synaptopodin**, thereby reducing proteinuria. **Analysis of Incorrect Options:** * **Option B (Inhibition of GMPD):** This refers to **Mycophenolate Mofetil (MMM)**, which inhibits Inosine Monophosphate Dehydrogenase (IMPDH), a rate-limiting step in guanosine nucleotide (GMP) synthesis. * **Option C (Alkylating agent):** This describes drugs like **Cyclophosphamide** and Chlorambucil, which work by cross-linking DNA strands. * **Option D (Antibiotic):** While some immunosuppressants are derived from fungi/bacteria (e.g., Sirolimus is a macrolide), Cyclosporine is classified as a Calcineurin Inhibitor (CNI), not an antibiotic. **High-Yield Clinical Pearls for NEET-PG:** * **Side Effects of Cyclosporine:** Gingival hyperplasia, hirsutism, nephrotoxicity (afferent arteriolar vasoconstriction), and hypertension. * **Tacrolimus** is another CNI (binds to FKBP-12) but is more potent and does not cause hirsutism or gingival hyperplasia (though it has a higher risk of post-transplant diabetes). * **Monitoring:** Therapeutic Drug Monitoring (TDM) is essential for Cyclosporine due to its narrow therapeutic index.

Question 1

Which of the following is a characteristic feature of Henoch-Schonlein purpura?

Accepted Answer

Palpable purpura

Answer

Occurs only in elderly persons

Answer

Thrombocytopenia

Answer

None of the above

Question 2

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

Accepted Answer

Presence of more than 5 WBC/HPF for girls and more than 3 WBC/HPF for boys

Answer

Infection can occur without pyuria

Answer

Pyuria may be present without urinary tract infection

Answer

Isolated pyuria is neither confirmatory nor diagnostic for urinary tract infection

Question 3

What is the most devastating consequence of hypernatremic dehydration in children?

Accepted Answer

Brain hemorrhage

Answer

Seizures

Answer

Hyperglycemia

Answer

Hypocalcemia

Question 4

Recurrent hematuria in a deaf-mute patient is seen in which of the following conditions?

Accepted Answer

Alport syndrome

Answer

Fanconi anemia

Answer

Renal tubular acidosis

Answer

Nephrotic syndrome

Question 5

What are the diagnostic criteria for post-streptococcal glomerulonephritis in children?

Accepted Answer

Mild proteinuria, hematuria, low ASO titre

Answer

Heavy proteinuria, high cholesterol, high ASO titre

Answer

Heavy proteinuria, hematuria, low ASO titre

Answer

Mild proteinuria, high cholesterol, normal ASO titre

Question 6

What is the most common cause of renovascular hypertension in children and young adults?

Accepted Answer

Fibromuscular dysplasia

Answer

Atherosclerotic disease

Answer

Ectopic kidney

Answer

Polycystic kidney disease

Question 7

A 10-year-old child with a history of sore throat one week ago presents with sudden onset of hematuria, generalized edema, and hypertension. Laboratory findings reveal proteinuria, red blood cell casts in the urine, deranged renal function tests, and low serum complement C3 levels. What is the most likely histological finding if a kidney biopsy is performed?

Accepted Answer

Diffuse proliferative glomerulonephritis

Answer

Minimal change disease

Answer

Focal segmental glomerulosclerosis

Answer

Membranous nephropathy

Question 8

Urinary retention in a child is most commonly caused by what condition?

Accepted Answer

Meatal stricture with ulceration

Answer

Posterior urethral valve

Answer

Urethral stricture

Answer

Epispadias

Question 9

Which of the following is true about a child with post-streptococcal glomerulonephritis?

Accepted Answer

Severe renal dysfunction is an indication for biopsy

Answer

Microscopic hematuria decreases within 4 weeks

Answer

Serum triglyceride levels increase

Answer

Serum C3 levels are normal

Question 10

Cyclosporine in nephrotic syndrome acts by which mechanism?

Accepted Answer

Inhibiting calcineurin

Answer

Inhibition of GMPD

Answer

Acting as an alkylating agent

Answer

Acting as an antibiotic

Nephrology — MCQs

Nephrology — MCQs

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