Addison's disease

Addison's disease is what happens when the adrenal cortex itself fails and can no longer make enough of its hormones. Because the damage is to the gland directly, both cortisol and aldosterone usually fall short, leaving the body unable to handle stress, maintain blood sugar, or hold onto salt. It tends to come on gradually with vague symptoms — fatigue, weakness, weight loss, low blood pressure, salt craving, and darkening of the skin.

It is called primary adrenal insufficiency to distinguish it from secondary forms (where the problem is too little ACTH from the pituitary). In primary disease the adrenal cortex is destroyed — most often by autoimmune attack in developed countries, or by infections such as tuberculosis elsewhere. A telltale clue is skin darkening: the failing gland cannot suppress ACTH, and the high ACTH stimulates skin pigment cells.

The most dangerous manifestation is an adrenal crisis — a sudden, severe shortfall of cortisol, often triggered by infection, injury, or surgery, producing profound low blood pressure, vomiting, and shock that can be fatal without prompt treatment. Management is lifelong hormone replacement with a glucocorticoid and, because aldosterone is also missing, a mineralocorticoid, with extra steroid doses during illness or stress.