17α-Hydroxypregnenolone is a pregnane (C21) steroid that is obtained by hydroxylation of pregnenolone at the C17α position.

This step is performed by the mitochondrial cytochrome P450 enzyme 17α-hydroxylase (CYP17A1) that is present in the adrenal and gonads.

Peak levels are reached in humans at the end of puberty and then decline.

As such 17α-hydroxypregenolone represents an intermediary in the Δ5 pathway that leads from pregnenolone to DHEA.

[2] In patients with congenital adrenal hyperplasia due to 3β-hydroxysteroid dehydrogenase deficiency 17α-hydroxypregnenolone is increased, while in patients with congenital adrenal hyperplasia due to 17α-hydroxylase deficiency levels are low to absent.