5-Androstenedione

5-Androstenedione is a steroid hormone that is a direct precursor of the hormone testosterone. It is synthesized in the adrenal glands, the gonads, and the brain. 5-Androstenedione is a major steroid produced by the adrenal cortex but is also produced by the testes and the ovaries.

Chemical Structure and Synthesis

5-Androstenedione is a 19-carbon steroid hormone. It is formed in the adrenal cortex under the influence of adrenocorticotropic hormone (ACTH). ACTH stimulates the conversion of cholesterol into pregnenolone, which is then converted into progesterone. Progesterone is then converted into 5-Androstenedione by the enzyme 3β-hydroxysteroid dehydrogenase.

Biological Function

5-Androstenedione is a key intermediate in the biosynthesis of the androgen and estrogen sex hormones. It serves as a direct precursor molecule for the production of testosterone, and indirectly for the production of the estrogens estrone and estradiol.

Clinical Significance

Abnormal levels of 5-Androstenedione can indicate disorders of the adrenal glands or gonads. Elevated levels of 5-Androstenedione are found in conditions such as polycystic ovary syndrome (PCOS), congenital adrenal hyperplasia (CAH), and adrenocortical carcinoma.

See Also

• Androstenedione
• Testosterone
• Estrone
• Estradiol
• Adrenocorticotropic hormone
• Polycystic ovary syndrome
• Congenital adrenal hyperplasia
• Adrenocortical carcinoma