✅ Model Answer:
• Diagnosis: Nephrotic syndrome (likely minimal change disease – most common in this age group).
• Evidence: Nephrotic-range proteinuria (P/C 4.5), hypoalbuminemia (1.8), edema (periorbital, ascites), hyperlipidemia (cholesterol 350), normal BP, no hematuria.
• Next step: Start prednisone 60 mg/m²/day (or 2 mg/kg/day) for 4-6 weeks. Sodium restriction, fluid restriction, diuretics for severe edema. Monitor for infections. Consider renal biopsy if atypical features (hypertension, hematuria, low C3, age <1 or >12 years).

✅ Model Answer:
• Most common cause: Minimal change disease (MCD) – accounts for 70-90% of nephrotic syndrome in children 1-10 years.
• Pathology: Normal glomeruli on light microscopy; diffuse effacement of podocyte foot processes on electron microscopy.
• Pathophysiology: T-cell dysfunction → increased production of cytokines (e.g., interleukin-13) → damage to podocyte slit diaphragm → loss of glomerular basement membrane negative charge → massive proteinuria (albuminuria).
• Response to steroids: Excellent response to corticosteroids (steroid-sensitive).
• Recurrence: Common (relapses occur in ~60-80% of children).

✅ Model Answer:
• Classic triad:
- Edema: Periorbital (worse in the morning), dependent edema (ankles, sacrum), ascites, pleural effusion, scrotal/labial edema.
- Proteinuria: Nephrotic-range (>3.5 g/1.73m²/day or P/C >2.0).
- Hypoalbuminemia: Serum albumin <2.5 g/dL.
• Other features:
- Hyperlipidemia.
- Frothy urine.
- Weight gain (due to fluid retention).
- Normal BP (in MCD; hypertension suggests other histology).
- No hematuria (in MCD; hematuria suggests other histology).

✅ Model Answer:
• Urinalysis: 3-4+ protein, no RBCs, no casts (in MCD).
• Urine P/C ratio: >2.0 (nephrotic-range).
• Serum albumin: <2.5 g/dL.
• Serum cholesterol: Elevated (>200 mg/dL).
• Serum creatinine: Normal or mildly elevated.
• Complement (C3, C4): Normal (in MCD; low suggests MPGN or lupus).
• Hepatitis B/C, HIV, ANA: If atypical features.
• Renal biopsy: Not routinely performed in children 1-10 years with classic MCD presentation. Indicated for:
- Age <1 year or >12 years.
- Hypertension, hematuria, low C3, renal insufficiency.
- Steroid-resistant or steroid-dependent nephrotic syndrome.

✅ Model Answer:
• First-line (steroids):
- Prednisone: 60 mg/m²/day (or 2 mg/kg/day) for 4-6 weeks, then taper over 2-3 months.
- Response: Proteinuria resolves in 80-90% within 4 weeks (steroid-sensitive).
• Supportive care:
- Sodium restriction: Avoid high-sodium foods.
- Fluid restriction: If severe edema.
- Diuretics: Furosemide (for severe edema) – use with caution (risk of hypovolemia).
- Albumin infusion: 25% albumin (for severe edema or ascites) – rarely needed.
- Antibiotic prophylaxis: Penicillin V for pneumococcal prophylaxis (if nephrotic syndrome is steroid-dependent).
• Relapses: Treated with steroids again (prednisone 60 mg/m²/day until remission, then taper).
• Steroid-resistant/dependent: Consider calcineurin inhibitors (cyclosporine, tacrolimus), mycophenolate mofetil, rituximab.

✅ Model Answer:
• Infections:
- Pneumococcal peritonitis (most feared complication).
- Cellulitis, sepsis.
- UTI.
- Varicella, measles.
- Prophylactic penicillin recommended for steroid-dependent patients.
• Thromboembolism:
- Renal vein thrombosis (most common).
- Pulmonary embolism, DVT.
- Risk factors: Severe hypoalbuminemia (<1.5 g/dL), hypercoagulability.
• Acute kidney injury (AKI): Hypovolemia, acute tubular necrosis.
• Hyperlipidemia: Long-term cardiovascular risk.
• Growth failure: From chronic steroid use and disease.
• Relapse: Frequent relapses (60-80% of children).
• Steroid toxicity: Cushingoid features, osteoporosis, hypertension, glucose intolerance.

✅ Model Answer:
• Prognosis:
- Excellent for steroid-sensitive MCD (90% respond to steroids).
- Relapses: Common (~60-80%), but usually respond to steroids.
- Frequent relapsers: May require steroid-sparing agents.
- Steroid-resistant: May progress to CKD/ESKD (10-20%).
- Life expectancy: Normal with treatment.
• Long-term follow-up:
- Monitor urine protein, BP, growth.
- Monitor for relapses.
- Monitor for steroid toxicity.
- Vaccinations: Pneumococcal, varicella, influenza (when off steroids).
- Genetic counseling if familial NS.

✅ Model Answer:
• Indications for renal biopsy:
- Age <1 year or >12 years (atypical age).
- Hypertension (at presentation).
- Hematuria (persistent microscopic or gross).
- Low C3 complement.
- Renal insufficiency (elevated creatinine).
- Steroid-resistant (no remission after 4-6 weeks of steroids).
- Steroid-dependent (multiple relapses).
- Suspected secondary causes (lupus, IgA, MPGN).
• Histology:
- MCD: Normal light microscopy, effacement of foot processes on EM.
- FSGS: Segmental sclerosis.
- MPGN: Membranoproliferative changes, low C3.
- MN: Membranous nephropathy – subepithelial deposits.
• Outcome: Guides treatment (steroids, immunosuppressants).