Blood-spot 17 alpha-hydroxyprogesterone radioimmunoassay in the follow-up of congenital adrenal hyperplasia.

The value of plasma 17 alpha-hydroxyprogesterone (17 alpha-OHP) concentration in monitoring the treatment of congenital adrenal hyperplasia (CAH) was studied by using a capillary blood micromethod. The blood-spot 17-OHP radioimmunoassay method involves serial sampling throughout the day and sending the samples into the centre by mail. Follow-up of seven children treated for CAH due to 21-hydroxylase deficiency showed that a single measurement of plasma 17-OHP concentration cannot be relied upon to determine adequacy of control, since circadian variation and timing of the sample in relation to the last dose of glucocorticoid may influence the plasma level of 17 alpha-OHP. Our data confirm the value of sequential 17 alpha-OHP assays throughout the day in the follow-up of CAH. With the blood-spot method the 17 alpha-OHP determinations can be used on a wide scale for monitoring therapy.