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). Serological workup shows negative ANA, negative ANCA, normal complement levels, and normal renal function. Renal biopsy shows diffuse podocyte foot process effacement on electron microscopy with no immune deposits on immunofluorescence. What is the most appropriate next step in management?

Explanation

## Diagnosis: Minimal Change Disease (MCD) The clinical and histopathological findings are pathognomonic for minimal change disease: - Nephrotic syndrome with preserved renal function - Negative serology (ANA, ANCA, normal complement) - Electron microscopy showing diffuse foot process effacement - **Absence of immune deposits** on immunofluorescence (key distinguishing feature) ## Management Algorithm for MCD ```mermaid flowchart TD A[Minimal Change Disease diagnosed]:::outcome --> B{Corticosteroid-responsive?}:::decision B -->|First episode| C[Prednisolone 1 mg/kg/day for 4-6 weeks]:::action C --> D[Taper over 2-3 months]:::action D --> E[Remission achieved]:::outcome B -->|Steroid-dependent/resistant| F[Add cyclophosphamide or calcineurin inhibitor]:::action ``` ## Key Point: **Corticosteroids are first-line therapy for MCD.** Most patients (>90%) respond to prednisolone monotherapy within 4–6 weeks. Cyclophosphamide is reserved for steroid-dependent or steroid-resistant disease. ## High-Yield: - MCD accounts for ~90% of nephrotic syndrome in children and ~40% in adults - Prognosis is excellent; complete remission is expected in >90% of first-episode cases - Immunosuppression is **not** indicated at diagnosis unless there is steroid resistance or dependence ## Clinical Pearl: The absence of immune deposits on immunofluorescence is critical for distinguishing MCD from membranoproliferative GN, membranous nephropathy, and IgA nephropathy—all of which show immune complex deposition.