In a screening program for renal disease in a tertiary care center in India, 100 patients with nephrotic syndrome were evaluated. Which of the following is the most common primary glomerulonephritis causing nephrotic syndrome in this Indian cohort?

Explanation

## Most Common Primary GN Causing Nephrotic Syndrome in India **Key Point:** Membranous nephropathy (MN) is the most common primary glomerulonephritis causing nephrotic syndrome in **adults** in India, consistent with global data. Large Indian registry studies (including data from AIIMS, PGI Chandigarh, and published Indian nephrology cohorts) consistently show membranous nephropathy accounting for approximately 30–40% of primary nephrotic syndrome in adults, followed by FSGS and minimal change disease. ### Pathological Features of Membranous Nephropathy | Feature | Finding | |---------|----------| | **Light Microscopy** | Diffuse thickening of GBM; "spike and dome" pattern on silver stain | | **Electron Microscopy** | Subepithelial electron-dense deposits; GBM spikes between deposits | | **Immunofluorescence** | Granular IgG and C3 along capillary walls (full-house pattern in secondary) | | **Clinical Presentation** | Nephrotic syndrome; usually without hematuria; insidious onset | ### Epidemiology in India vs. Western Countries | Feature | India (Adults) | Western Countries (Adults) | |---------|----------------|---------------------------| | **Most common primary GN with nephrotic** | Membranous nephropathy (~30–40%) | Membranous nephropathy (~30–40%) | | **Second most common** | FSGS (~20–30%) | FSGS (~20–25%) | | **Minimal change disease** | More common in children | More common in children | | **IgA nephropathy** | Common cause of nephritic, not nephrotic | Common cause of nephritic, not nephrotic | **High-Yield:** Membranous nephropathy is the leading cause of primary nephrotic syndrome in adults both globally and in India. It is caused by anti-PLA2R antibodies in ~70–80% of idiopathic cases (Harrison's Principles of Internal Medicine, 21e). FSGS is the predominant cause in African-American populations and in HIV-associated nephropathy (HIVAN), but this represents a **secondary** cause, not primary GN. ### Why Membranous Nephropathy Leads in Indian Adults 1. **Age distribution:** MN predominantly affects adults (peak 40–60 years), the dominant group in tertiary care nephrology cohorts 2. **Anti-PLA2R antibody-mediated:** Idiopathic MN is the most common primary form 3. **Indian registry data:** Studies from AIIMS and PGI Chandigarh confirm MN as the leading primary cause of adult nephrotic syndrome 4. **FSGS in India:** Much of the FSGS burden is *secondary* (HIV-HIVAN, obesity, hypertension) — when restricted to *primary* GN, MN predominates ### Important Distinction - **Primary (idiopathic) FSGS** is less common than membranous nephropathy in Indian adults - **Secondary FSGS** (HIV, obesity, reflux nephropathy) should not be counted when the question specifies *primary* glomerulonephritis - **IgA nephropathy** is the most common primary GN overall but typically presents as **nephritic** syndrome, not nephrotic **Clinical Pearl:** In children, minimal change disease (MCD) is the most common cause of nephrotic syndrome. In adults (including Indian adults), membranous nephropathy takes the lead for primary GN. This age-based distinction is a classic NEET PG high-yield point (Robbins Basic Pathology, 10e, Ch. 20; Harrison's 21e, Ch. 305). [cite: Robbins Basic Pathology 10e Ch 20; Harrison's Principles of Internal Medicine 21e Ch 305]