Secondary Adrenal Insufficiency Presenting With Severe Hyponatremia in an Elderly Patient With Primary Aldosteronism Suggesting Underlying Autonomous Cortisol Secretion.

Possible unrecognized cortisol autonomy in primary aldosteronism may suppress the hypothalamic-pituitary-adrenal axis. Under physiological stress, this may contribute to secondary adrenal insufficiency and severe hyponatremia. Clinicians should consider adrenal insufficiency in patients with primary aldosteronism presenting with unexplained clinical deterioration.