What is it: Pregnenolone is a steroid prohormone that leads to the production of progesterone, mineral corticoids, glucocorticoids, androgens, and estrogens. In humans, steroid hormones are produced by the adrenal glands and the gonads. The formation of Pregnenolone from cholesterol is the first step in steroid genesis and is mediated by the proteolytic enzyme, single cholesterol side-chain cleavage enzyme (P450 scc). Steroid genesis continues along two paths from Pregnenolone. By the enzymatic action of 17α-hydroxylase (17α-H) and 3β-hydroxysteroid Dehydrogenase (3β-HSD) 17-Hydroxypregnenolone and progesterone are produced, respectively.
Tested for: identifying the effects of increased cortisone demand, insufficient hormone production
Increased in: Since the various forms of congenital adrenal hyperplasia (CAH) result from enzymatic defects in the adrenal steroidogenic pathways, elevated levels of Pregnenolone levels may be useful in their diagnosis.
Decreased in: Levels can be suppressed with dexamethasone inhibition and increased with exogenous ACTH stimulation.
Info: Pregnenolone levels have been shown to remain in the normal range in patients with Cushing syndrome and hyperaldosteronism.