What does the 17-Hydroxyprogesterone test measure?

Why is 17-Hydroxyprogesterone measured?

Measurement of 17-OHP is the cornerstone of screening and diagnosis for 21-hydroxylase-deficient congenital adrenal hyperplasia, both in newborns and in children or adults with suspected non-classic forms. Marked basal elevations confirm classic CAH, while borderline or moderately raised values often require ACTH stimulation testing to distinguish heterozygotes and non-classic cases from unaffected individuals. The test is also used to monitor replacement therapy in known CAH, where the goal is to suppress 17-OHP into the upper-normal range without overtreatment.

Reference ranges

Standard reference

Follicular phase <200 ng/dL, luteal phase <285 ng/dL, postmenopausal <51 ng/dL; prepubertal children <100 ng/dL. Values are sex-, age-, menstrual phase-, and assay-dependent.

Functional medicine optimal

In the context of CAH screening, unstimulated morning 17-OHP below 200 ng/dL in the follicular phase is reassuring; values above 1,000 ng/dL are highly suggestive of classic CAH, and intermediate results warrant dynamic testing. Optimal therapeutic targets in treated CAH patients are debated but generally aim for concentrations in the high-normal to two- to threefold-elevated range to balance androgen suppression against glucocorticoid excess.

Units

ng/dL, nmol/L

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.