## Why "Initiate prednisone 1 mg/kg/day for 4–6 weeks" is right The clinical presentation—nephrotic syndrome in a child with normal light microscopy, negative immunofluorescence, and **electron microscopy showing diffuse effacement (flattening) of podocyte foot processes (structure C)**—is pathognomonic for Minimal Change Disease (MCD). The slit diaphragm proteins (nephrin and podocin) at the foot process interface are intact structurally but functionally compromised, causing loss of the charge-selective barrier and selective proteinuria (predominantly albumin). MCD is the most common cause of nephrotic syndrome in children and is highly steroid-responsive. First-line treatment is prednisone 1 mg/kg/day (maximum 80 mg) for 4–6 weeks, with 80–90% remission rates. (Guyton & Hall 14e Ch 27; Robbins 10e Ch 20) ## Why each distractor is wrong - **Perform renal angiography to assess for renal artery stenosis**: Renal artery stenosis causes hypertension and reduced GFR, not nephrotic syndrome with normal creatinine. No clinical or imaging indication here. - **Start cyclophosphamide and azathioprine immediately**: These are reserved for steroid-resistant MCD (10–20% of cases) or for other glomerulonephritides (e.g., FSGS, membranoproliferative GN). First-line therapy is always steroids in MCD. - **Refer for urgent plasmapheresis and immunosuppression**: Plasmapheresis is indicated in rapidly progressive GN (RPGN) with crescents or severe vasculitis, not in MCD. MCD has an excellent prognosis with steroids alone. **High-Yield:** Foot process effacement on EM + normal light microscopy + negative IF + steroid responsiveness = Minimal Change Disease in a child with nephrotic syndrome. [cite: Guyton & Hall 14e Ch 27; Robbins 10e Ch 20]
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