Adrenal insufficiency in a man with non-classical 21-hydroxylase deficiency: consequence or coincidence?

Deficiency of the adrenal enzyme 21-hydroxylase, which is required for cortisol synthesis, appears in two forms: a rare classical variant with severe enzyme deficiency, usually presenting in neonates with ambiguous genitalia (from androgen overproduction) or adrenal crisis (from glucocorticoid and mineralocorticoid underproduction), and a common (1% of the general population) non-classical variant with mild enzyme deficiency, usually presenting in young adults with findings of androgen excess but without clinical evidence of decreased steroid hormone production. We describe a 22-year-old man who had clinical and biochemical findings consistent with adrenal insufficiency, including a favorable response to hydrocortisone replacement, in whom elevated serum levels of the cortisol precursor 17-hydroxyprogesterone were diagnostic of non-classical 21-hydroxylase deficiency and in whom no other cause of adrenal insufficiency could be identified. These findings raise the possibility that non-classical 21-hydroxylase deficiency, an extremely frequent disorder which is generally thought to be without significant morbidity, might cause or contribute to adrenal insufficiency in adults.