Androstenedione

Androstenedione (also known as 4-androstenedione) is a 19-carbon steroid hormone produced in the adrenal glands and the gonads as an intermediate step in the biochemical pathway that produces the androgen testosterone and the estrogens estrone and estradiol.

Synthesis
It is the common precursor of male and female sex hormones. Some androstenedione is also secreted into the plasma, and may be converted in peripheral tissues to testosterone and estrogens.

Androstenedione originates either from the conversion of dehydroepiandrosterone or from 17-hydroxyprogesterone. It is further converted to either testosterone or estrone.

The production of adrenal androstenedione is governed by ACTH, while production of gonadal androstenedione is under control by gonadotropins. In premenopausal women the adrenal glands and ovaries each produce about half of the total androstendione (about 3 mg/day). After menopause androstenedione production is about halved, primarily due to the reduction of steroid secreted by the ovary. Nevertheless, androstenedione is the principal steroid produced by the postmenopausal ovary.

Androstenedione as a supplement
Androstenedione is manufactured as dietary supplement, often called andro (or andros) for short. Andro was in common use in Major League Baseball throughout the 1990s by record breaking sluggers like Mark McGwire, but it is unknown (and unknowable) to what extent andro was responsible for McGwire's exceptional performance. The supplement is banned by the World Anti-Doping Agency, and hence from the Olympic Games.

On March 12, 2004, the Anabolic Steroid Control Act of 2004 was introduced into the United States Senate. It amended the Controlled Substance Act to place both anabolic steroids and prohormones on a list of controlled substances, making possession of the banned substances a federal crime. The law took effect on January 20, 2005.

On April 11, 2004, the United States Food and Drug Administration banned the sale of Andro, citing that the drug poses significant health risks commonly associated with steroids.

Conversion to estrone
Because androstenedione is converted in part to estrogens, persons taking this supplement may have estrogenic side effects. A visible problem could be gynecomastia (formation of breast tissue) in males.