## Most Common Cause of Primary Adrenal Insufficiency in India **Key Point:** Tuberculosis (TB) remains the most common cause of primary adrenal insufficiency (Addison's disease) in India and other endemic regions, accounting for 70–90% of cases in developing countries. **Clinical Pearl:** TB typically causes bilateral adrenal destruction through caseating granulomas, leading to loss of both cortisol and aldosterone production. Patients present with the classic triad of hyperpigmentation (due to elevated ACTH stimulating melanocytes), hypotension (from aldosterone deficiency), and hyponatremia. **High-Yield:** The distinction between primary and secondary adrenal insufficiency is critical: - **Primary (low cortisol + high ACTH):** Direct adrenal gland failure → TB, autoimmune, infiltration - **Secondary (low cortisol + low ACTH):** Pituitary/hypothalamic dysfunction ### Comparison of Causes of Primary Adrenal Insufficiency | Cause | Frequency (Developed) | Frequency (India/Endemic) | Key Feature | |-------|----------------------|---------------------------|-------------| | Tuberculosis | 10–15% | 70–90% | Bilateral caseating granulomas | | Autoimmune adrenalitis | 70–80% | 5–10% | Adrenal antibodies, associated autoimmune diseases | | Adrenal metastases | 5–10% | 2–5% | History of malignancy, usually unilateral initially | | Adrenoleukodystrophy | Rare | Rare | X-linked, neurological symptoms, elevated VLCFA | **Mnemonic — Causes of Primary Adrenal Insufficiency (TACO):** - **T**uberculosis (most common in endemic regions) - **A**utoimmune (most common in developed countries) - **C**ancer (metastases) - **O**ther (infiltrative, hemorrhage, adrenoleukodystrophy) **Clinical Pearl:** In an Indian patient with adrenal insufficiency, always screen for TB with chest X-ray, sputum smear, and TB-IGRA. Adrenal TB often occurs without active pulmonary TB.
Sign up free to access AI-powered MCQ practice with detailed explanations and adaptive learning.