Which of the following is the most common cause of primary adrenal insufficiency (Addison disease) in India?

Explanation

## Epidemiology of Addison Disease in India **Key Point:** Tuberculosis is the leading cause of primary adrenal insufficiency in developing countries, including India, accounting for 20–40% of cases in endemic regions. ### Causes of Primary Adrenal Insufficiency | Cause | Prevalence (Developed) | Prevalence (India/Developing) | Pathophysiology | |-------|------------------------|-------------------------------|------------------| | Autoimmune adrenalitis | 70–80% | 10–20% | Antibodies to 21-hydroxylase (CYP21A2) | | Tuberculosis | 10–15% | 20–40% | Caseating granulomas → bilateral adrenal destruction | | Fungal infection | <5% | Variable (endemic areas) | Histoplasmosis, blastomycosis, coccidioidomycosis | | Adrenal lymphoma | <5% | <5% | Infiltration of adrenal tissue | | Adrenoleukodystrophy | <5% | <5% | X-linked peroxisomal disorder | **High-Yield:** In India and other TB-endemic regions, always suspect tuberculosis in a patient presenting with Addison disease. TB typically causes bilateral adrenal destruction with caseating granulomas visible on imaging or histology. ### Clinical Pearl **Clinical Pearl:** Patients with TB-induced Addison disease often have: - History of pulmonary or extrapulmonary TB - Bilateral adrenal enlargement on CT (early) → shrinkage and calcification (late) - Positive TB culture or PCR from adrenal tissue or sputum - Response to antituberculous therapy may improve adrenal function in early disease **Mnemonic:** **FACT** — Fungal, Autoimmune, Carcinoma/TB, Tuberculosis (in endemic regions TB is #1).