In Addison disease with hyperkalemia, hyponatremia, and hypotension, which organ dysfunction is primary?

• A. Adrenal medulla
• B. Hypothalamus
• C. Adrenal cortex
• D. Pituitary

Answer: (C)

The main concept is that primary adrenal insufficiency directly damages the adrenal cortex, leading to loss of both cortisol and aldosterone. In Addison disease, destruction of the cortex reduces aldosterone production, causing salt wasting with hyponatremia and hyperkalemia, and it reduces cortisol as well, contributing to hypotension from decreased vascular tone and volume status. If the problem were in the adrenal medulla, hypothalamus, or pituitary, the pattern would be different: adrenal medulla issues affect catecholamines and don’t explain the electrolyte disturbances; hypothalamic or pituitary dysfunction causes secondary adrenal insufficiency where aldosterone is usually preserved (RAAS still works), so hyperkalemia and severe hyponatremia are less typical. Therefore, the correct organ involved is the adrenal cortex.