The application of a serum 17OH-progesterone radioimmunoassay to the diagnosis and management of congenital adrenal hyperplasia.

Serum concentrations of 17OH-progesterone were studied serially over 24 hours in 13 treated and untreated patients with the C21 hydroxylase form of congenital adrenal hyperplasia. The results were correlated with measurements of plasma renin activity, serum electrolytes, and urinary 17-ketosteroids and pregnanetriol. In 500 healthy subjects from birth to adult life, serum 17OH-pregesterone levels ranged from 5 to 315 ng/dl. In untreated CAH, serum 17OH-progesterone was markedly elevated (2,000 to 80,000 ng/dl). Treatment with cortisol (20 to 30 mg/m2/day in 3 doses) resulted in normal serum 17OH-progesterone levels in both non-salt-losing and salt-losing patients receiving adequate mineralocorticoid. Even slightly inadequate mineralocorticoid therapy (shown by high plasma renin activity with normal serum electrolytes) was associated with elevated 17OH-progesterone (to 65,000 ng/dl) in spite of usually effective doses of cortisol. Some patients showed isolated 17OH-progesterone elevations (usually early morning), a situation which requires only revision of the cortisol dosage schedule without an increase in total dosage. The data confirm the value of 17OH-progesterone assays in both the diagnosis and management of CAH. Taken together with determinations of plasma renin activity, serum 17OH-progesterone assays can permit more exact control of CAH without excessive doses of glucocorticoid.