17-OHP is an endogenous progestogen produced from 17-hydroxypregnenolone and progesterone, via the actions of 3β-hydroxysteroid dehydrogenase and 17-hydroxylase. 17-OHP synthesis is stimulated by pituitary adrenocorticotrophic hormone (ACTH), as part of the hypothalamic–pituitary–adrenal axis.
17-OHP is primarily produced within the zona fasciculata of the adrenal cortex. It can also be produced by the corpus luteum, gonads, and placenta. 17-OHP is an intermediate in the production of cortisol in the zona fasciculata, and an intermediate in the production of adrenal androgens in the zona reticularis (via 17,20 lyase) and 17αhydroxyallopregnanolone (via 5α-reductase). 17-OHP is a relatively weak agonist of the progesterone receptor, a partial agonist of the glucocorticoid receptor, and an antagonist of the mineralocorticoid receptor.
Concomitant corticosteroid treatment and pituitary dysfunction can suppress 17-OHP.
The measurement of 17-OHP is most commonly used for the investigation of CAH, as its accumulation is associated with deficiencies of several enzymes involved in steroid biosynthesis – the most common of these being 21-hydroxylase (CYP21A2) deficiency.
17-OHP measurement can aid in the investigation of patients with disorders of sexual differentiation, ambiguous genitalia, clitoromegaly, salt-wasting dehydration, symptoms of androgen excess, and premature adrenarche or precocious puberty. 17-OHP measurements, along with measurements of renin, can also be used for the monitoring of hydrocortisone replacement in these patients. A normal basal 17-OHP concentration does not exclude non-classical CAH.
15 working days
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