17ñ-Hydroxyprogesterone (17ñ-OHP), also known as 17-OH progesterone (17-OHP), or hydroxyprogesterone (OHP), is an endogenous progestogen steroid hormone related to progesterone. It is also a chemical intermediate in the biosynthesis of many other endogenous steroids, including androgens, estrogens, glucocorticoids, and mineralocorticoids, as well as neurosteroids.
17ñ-OHP is an agonist of the progesterone receptor (PR) similarly to progesterone, albeit weakly in comparison. In addition, it is an antagonist of the mineralocorticoid receptor (MR) as well as a partial agonist of the glucocorticoid receptor (GR), albeit with very low potency (EC<sub>50</sub> >100-fold less relative to cortisol) at the latter site, also similarly to progesterone.
17ñ-OHP is derived from progesterone via 17ñ-hydroxylase (encoded by CYP17A1).
17ñ-OHP increases in the third trimester of pregnancy primarily due to fetal adrenal production.
This steroid is primarily produced in the adrenal glands and to some degree in the gonads, specifically the corpus luteum of the ovary. Normal levels are 3-90 ng/dl in children, and in women, 20-100 ng/dl prior to ovulation, and 100-500 ng/dl during the luteal phase.
Measurements of levels of 17ñ-OHP are useful in the evaluation of patients with suspected congenital adrenal hyperplasia as the typical enzymes that are defective, namely 21-hydroxylase and 11ò-hydroxylase, lead to a build-up of 17ñ-OHP. In contrast, the rare patient with 17ñ-hydroxylase deficiency will have very low or undetectable levels of 17ñ-OHP. 17ñ-OHP levels can also be used to measure contribution of progestational activity of the corpus luteum during pregnancy as progesterone but note, 17ñ-OHP is also contributed by the placenta.
Immunoassays like RIA (radioimmunoassay) or IRMA (immunoradiometric assay) used to clinically determine 17ñ-OHP are prone to cross-reactivity with the 17ñ-OHP steroid precursors and their sulphated conjugates. Gas or liquid chromatography and mass spectrometry (e.g. LC-MS/MS) achieves greater specificity than immunoassays.
Measurement of 17ñ-OHP by LC-MS/MS improves newborn screening for congenital adrenal hyperplasia due to 21-hydroxylase deficiency, because 17ñ-OHP steroid precursors and their sulphated conjugates which are present in the first two days after birth and longer in pre-term neonates, cross-react in immunoassays with 17ñ-OHP, giving falsely high 17ñ-OHP levels.
Although 17ñ-OHP has not been used as a medication, its pharmacokinetics have been studied and reviewed.
Esters of 17ñ-OHP, such as hydroxyprogesterone caproate and, to a far lesser extent, hydroxyprogesterone acetate and hydroxyprogesterone heptanoate, have been used in medicine as progestins.
17ñ-OHP is the parent compound of a class of progestins referred to as the 17ñ-hydroxyprogesterone derivatives. Among others, this class of drugs includes chlormadinone acetate, cyproterone acetate, hydroxyprogesterone caproate, medroxyprogesterone acetate, and megestrol acetate.
Hydroxyprogesterone is the generic name of 17ñ-OHP and its and .