Test #140707A test to measure levels of pregnenolone in the blood.
In humans, steroid hormones are produced by the adrenal glands and the gonads.1,2 The formation of pregnenolone from cholesterol is the first step in steroidogenesis and is mediated by the proteolytic enzyme, single cholesterol side-chain cleavage enzyme (P450 scc). Steroidogenesis continues along two paths from pregnenolone. 17-Hydroxypregnenolone is produced from pregnenolone through the enzymatic action of 17?-hydroxylase (17?-H). Alternatively, pregnenolone is converted to progesterone through the enzymatic action of 3?-hydroxysteroid dehydrogenase (3?-HSD).Pregnenolone levels have been shown to remain in the normal range in patients with Cushing syndrome and hyperaldosteronism.3,4 Levels can be suppressed with dexamethasone inhibition and increased with exogenous ACTH stimulation.3 Pregnenolone levels have been shown to be elevated in patients with idiopathic hirsutism.4Since the various forms of congenital adrenal hyperplasia (CAH) result from enzymatic defects in the adrenal steroidogenic pathways, measurement of pregnenolone levels can be useful in diagnosis. Pregnenolone levels tend to be elevated in several forms of CAH, particularly in 17?-H deficiency and 3?-HSD deficiency since these enzymes catalyze steps immediately after pregnenolone in the steroidogenic pathways.2
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