Hydroxypregnenolone

Hydroxypregnenolone is a steroid that is synthesized from cholesterol. It is a precursor to many other important hormones, including progesterone, cortisol, and aldosterone.

Synthesis

File:Hydroxypregnenolone synthesis pathway.svg

Synthesis pathway of hydroxypregnenolone from cholesterol.

The synthesis of hydroxypregnenolone begins with the conversion of cholesterol to pregnenolone by the enzyme cholesterol side-chain cleavage enzyme (also known as P450scc). Pregnenolone is then converted to hydroxypregnenolone by the enzyme 17α-hydroxylase/C17-20 lyase.

Function

Hydroxypregnenolone serves as a critical intermediate in the biosynthesis of several steroid hormones. It is converted to dehydroepiandrosterone (DHEA) by the enzyme 17,20-lyase, and to progesterone by the enzyme 3β-hydroxysteroid dehydrogenase/Δ5-4 isomerase. DHEA and progesterone are then further metabolized to produce a variety of other hormones, including cortisol, aldosterone, and the sex steroids estrogen and testosterone.

Clinical significance

Abnormal levels of hydroxypregnenolone can be indicative of several medical conditions. Elevated levels may be seen in congenital adrenal hyperplasia, a group of genetic disorders that affect the adrenal glands. Reduced levels may be associated with Addison's disease, a condition characterized by insufficient production of steroid hormones by the adrenal glands.

See also

• Steroidogenesis
• Steroid hormone
• Adrenal gland