A 32-year-old woman presents with nephrotic syndrome (serum albumin 2.1 g/dL, 24-hour urine protein 8.5 g, serum creatinine 0.9 mg/dL). Kidney biopsy shows diffuse proliferative glomerulonephritis with subepithelial 'hump' deposits on electron microscopy. What is the drug of choice for initial immunosuppressive therapy?

Explanation

## Post-Infectious Glomerulonephritis (PIGN) — First-Line Treatment ### Clinical Context The 'hump' deposits on electron microscopy are pathognomonic for post-streptococcal glomerulonephritis (PSGN). The patient has nephrotic-range proteinuria and preserved renal function — a favourable prognostic profile. ### Drug of Choice: Corticosteroids **Key Point:** Corticosteroids (typically methylprednisolone 1 g IV daily × 3 days, then oral prednisolone 0.5–1 mg/kg/day tapering over 6–12 weeks) are the first-line immunosuppressive agent in PSGN with nephrotic syndrome. **High-Yield:** PSGN is self-limited in most children and adults; the majority achieve complete remission with supportive care (salt restriction, diuretics, ACE-I/ARB) and corticosteroids alone. Aggressive immunosuppression is reserved for: - Rapidly progressive glomerulonephritis (RPGN) features (crescent >50%) - Rapidly declining renal function - Persistent nephrotic syndrome after 6–8 weeks of steroids ### Why Corticosteroids Work They suppress the Th1/Th17 response and reduce complement-mediated inflammation, accelerating resolution of immune complex deposition and reducing proteinuria. ### Supportive Measures - ACE inhibitors or ARBs (reduce proteinuria and glomerular hyperfiltration) - Diuretics and salt restriction (manage oedema) - Statins (dyslipidaemia) - Anticoagulation (if serum albumin <2.0 g/dL and high thrombotic risk) [cite:Robbins 10e Ch 20]