Epitestosterone is a natural steroid, an inactive epimer of the hormone testosterone. Structurally, it differs from testosterone only in the configuration at the OH-bearing carbon, C17. Epitestosterone is believed to form in a similar way to testosterone; a 1993 study found that around 50% of epitestosterone production in human males can be ascribed to the testis,^[1] although the exact pathway of its formation is still the subject of research. It has been shown to accumulate in mammary cyst fluid and in the prostate.^[2] Epitestosterone levels are typically highest in young males; however, by adulthood, most healthy males exhibit a testosterone to epitestosterone ratio (T/E ratio) of about 1:1.^[3] The regulation of therapeutic goods, that is drugs and therapeutic devices, varies by jurisdiction. ... In pharmacology and toxicology, a route of administration is the path by which a drug, fluid, poison or other substance is brought into contact with the body 1. ... Steroid skeleton of lanosterol. ... In chemistry, an epimer is a stereoisomer that has a different configuration at only one of several stereogenic centers. ... Testosterone is a steroid hormone from the androgen group. ... The prostate is a compound tubuloalveolar exocrine gland of the male mammalian reproductive system. ...

Epitestosterone and testosterone

It has been shown that exogenous administration of testosterone does not affect levels of epitestosterone in the body. As a result, tests to determine the ratio of testosterone to epitestosterone in urine are used to find athletes who are doping.^[4] Most persons have a ratio of about 1:1 testosterone to epitestosterone (T/E ratio) in their urine. However, it is not uncommon to find T/E ratios of up to 4:1 and even T/E ratios of 10:1 can be normal for some individuals. T/E tests are most common because a person may naturally have high levels of testosterone, but even so T/E ratios tend to stay close to 1:1. Exogenous (or exogeneous) (from the Greek words exo and gen, meaning outside and production) refers to an action or object coming from outside a system. ... Testosterone is a steroid hormone from the androgen group. ... This article or section is in need of attention from an expert on the subject. ... This article needs additional references or sources for verification. ...

Epitestosterone has not been shown to enhance athletic performance, although administration of epistestosterone can be used to mask a high level of testosterone if the standard T/E ratio test is used. As such, epitestosterone is banned by many sporting authorities as a masking agent for testosterone.

In 1996 the US athlete Mary Decker failed a T/E test with a T/E ratio of greater than 6, the limit in force at the time. She took the case to arbitration, arguing that birth control pills can cause false positives for the test, but the arbitration panel ruled against her. Mary Slaney (born Mary Teresa Decker August 4, 1958) is an American former track and field athlete, who holds seven American records in her sport. ... A false positive, also called false alarm, exists when a test reports, incorrectly, that it has found a signal where none exists in reality. ...

In 2006, Floyd Landis stands to lose his Tour de France title after a second test showing an elevated T/E ratio. Test results from Floyd Landis' "A" test sample indicated that while the ratio was 11:1, his testosterone level was in the normal range and the problem was actually a deficient level of epitestosterone. Landis won the 17th stage of the tour; however, tests taken immediately after the stage victory showed a T/E ratio of 11:1^[5], more than double the 4:1 imposed limit (recently lowered from prior limits of 8:1 and 6:1). Landis has emphatically denied the charge, pointing out the scientific data that testosterone cannot enhance athletic performance unless taken over an extended period of time with regular doses. Despite his denial of the doping allegation, Landis was found guilty and stripped of his title in September 2007. Floyd Landis (born October 14, 1975) is an American cyclist. ... The 2006 Tour de France was the 93rd Tour de France, taking place from July 1 to July 23, 2006. ...

External links

• Landis has T/E ratio twice the tour limit
• Institute of Endocrinology Abstract on Epistestosterone
• Sex, drugs and sports: Prostaglandins, epitestosterone and sexual development
• Endocrine Functions in Male and Female Homosexuals
• Homosexual women: an endocrine and psychological study.

Notes