17α-Hydroxyprogesterone (17-α-hydroxy progesterone, 17α-OHP) is produced by the adrenal cortex and gonads, with very low progesterone activity. 17α-OHP is converted to the cortisol precursor compound S (CpS) via 21-hydroxylation. 17α-OHP has a diurnal rhythm consistent with adrenal cortisol. In adult women of reproductive age, 17α-OHP concentrations vary with the menstrual cycle, being higher in the luteal phase than in the follicular phase. During pregnancy, the fetus, placenta, and adrenal glands can produce large amounts of 17α-OHP. After 32 weeks of pregnancy, 17α-OHP concentrations increase sharply until delivery, and 17α-OHP is also present in the umbilical cord blood of newborns.

Women of reproductive age: follicular phase 0.1-0.8 ng/mL; luteal phase 0.27-2.9 ng/mL; last 3 months of pregnancy 2-12 ng/mL.

Men: 0.31-2.13 ng/mL.

Patients with congenital adrenal hyperplasia due to 21-hydroxylase deficiency have significantly elevated blood 17α-OH-P concentrations, while 17α-OH-P increases to a lesser extent in 11-hydroxylase deficiency. About 6% of adult women with hirsutism have varying degrees of 21-hydroxylase deficiency. In these cases of late-onset deficiency, 17P concentrations often exceed the upper limit of the follicular phase, 0.9 ng/mL. 17α-OH-P measurement is also used to analyze common acne in men and women, male baldness, and some unexplained infertility.