Androstenedione, andro for short, is a steroid hormone naturally produced in both men and women. Androstenedione produced in the body is converted to either testosterone or to an estrogen. It was widely available as a dietary supplement and primarily marketed to athletes and bodybuilders in the belief that taking it will increase strength, stamina and muscle mass.
Androstenedione is synthesized in the adrenal gland and gonads from dehydroepiandrosterone (DHEA). It is metabolized by the enzyme 17 beta-hydroxy steroid dehydrogenase to testosterone, and by the aromatase enzyme complex to estrone. Estrone is metabolized to estradiol.
Androstenedione was classified as a dietary supplement under the Dietary Supplement Health and Education Act of 1994 up until mid 2004. The once over the counter dietary supplement is no longer available.
MGH research shows androstenedione can raise testosterone levels
A study led by researchers from the Massachusetts General Hospital (MGH) has found that 300 milligram (mg) doses of androstenedione can raise blood testosterone levels in healthy young men. The report, in the Feb. 9 issue of the Journal of the American Medical Association also showed an increase in estrogen levels with both 100 and 300 mg doses. It did not examine whether taking androstenedione increases strength or muscle mass or whether androstenedione has long-term side effects.
The MGH-led study was designed only to test the claim that taking oral androstenedione supplements would raise testosterone levels. The research team led by Benjamin Leder, MD, also of the MGH Endocrine Unit enrolled 42 healthy men aged 20 to 40 with no previous history of taking androstenedione, steroids or any medication known to affect steroid levels. Participants were divided randomly into three groups: 15 received 100 mg daily doses of androstenedione, 14 received 300 mg doses of androstenedione, and 13 received no androstenedione. During the seven-day study, blood tests taken at frequent intervals after participants took the capsules measured levels of four hormones: androstenedione, testosterone and the estrogens estrone and estradiol.
While the 100 mg doses had no significant effect on testosterone levels, the 300 mg doses increased testosterone levels by an average of 34 percent. In one-third of those taking the 300 mg doses, testosterone levels exceeded the normal range for men. Testosterone levels returned to normal within a day of androstenedione administration. Estrogen levels also increased in both the 100 and 300 mg groups: estrone increased 74 percent at 100 mg and 196 percent at 300 mg, and estradiol increased 42 percent at 100 mg and 128 percent at 300 mg.
While this study examined only the direct effect of androstenedione on hormone levels, the authors noted that long-term increases in testosterone or estrogen can have serious side effects in certain susceptible patient populations. Elevated testosterone levels can lower levels of HDL (or "good") cholesterol and can have masculinizing effects on women. Men with increased estrogen levels can experience feminizing effects such as the growth of breasts. Young people who have elevated levels of either hormones could develop early puberty and a premature cessation of bone growth, leading to shorter-than-normal adult height.
The authors also note that the effects of androstenedione were different for different individuals. Some participants developed higher or lower hormone levels, suggesting that certain people may be more or less sensitive to the hormonal effects of androstenedione.
It has been claimed that supplemental androstenedione can significantly increase blood testosterone levels and therefore build muscle mass. Recent research is conflicting with respect to the testosterone effect, but is unified in suggesting that prolonged use of this steroid could result in serious health risks.
Some have suggested that more research is also needed to determine whether androstenedione may have some usefulness in those with low and declining testosterone levels, such as some women and older men. There is some evidence that supplementation with the steroid in doses under 300 milligrams a day might increase serum testosterone levels in those who are hypotestosterogenic.
The marketed supplement is synthetic. It is a solid lipophilic substance nearly insoluble in water.
Children, adolescents, pregnant women and nursing mothers should avoid androstenedione supplements.
Potential Side Effects
No data are available on the long-term safety of taking supplemental androstenedione. Adverse effects of exogenous testosterone in men include acne, testicular atrophy, gynecomastia, behavioral changes and possibly an increased risk of prostate cancer. Adverse effects of exogenous testosterone in women include hirsutism, deepening of the voice, acne, clitoral hypertrophy, amenorrhea, male-pattern baldness and coarsening of the skin. In adolescents, exogenous testosterone can lead to early closing of bone growth plates and decreased adult height. Other adverse effects of testosterone include hepatic failure and increased platelet aggregation.
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