androstenediona

Androstenedione, also known as 4-androstene-3,17-dione, is an endogenous steroid hormone that functions as a weak androgen and as a key precursor in steroidogenesis. It is produced mainly in the adrenal cortex and gonads, with additional synthesis in adipose tissue. In the body, androstenedione can be converted to testosterone by 17β-hydroxysteroid dehydrogenase or to estrogens (estrone and then estradiol) via aromatase. Thus it acts primarily as a biosynthetic intermediate rather than as a strong hormone on its own.

Biosynthesis and metabolism involve cholesterol as the starting point. From cholesterol, precursor steroids are formed through enzymatic steps, with androstenedione lying between DHEA and downstream androgens and estrogens. The relative importance of androstenedione as a circulating hormone varies with age, sex, and physiological state. In men, it contributes modestly to testosterone production; in women, it can supply substrate for estrogen synthesis and influence androgenic activity in peripheral tissues. Clinically, measurements of androstenedione can be used in endocrine evaluations to assess adrenal and gonadal function.

Historical and regulatory context: androstenedione has been marketed as a dietary supplement in the past, especially for athletic performance and muscle growth. Regulatory status varies by country; in the United States, anabolic steroid precursors were subject to increasing oversight in the 2000s. The safety profile is a consideration, as excessive intake can disrupt hormonal balance and cause androgenic or estrogenic side effects, along with potential cardiovascular or hepatic risks in some individuals.

Chemical identity: IUPAC name is 4-androsten-3,17-dione; synonyms include androstenedione and 4-AD. It is produced endogenously and participates in broader steroid metabolism.