Epitestosterone
Encyclopedia
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, 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
. 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.
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
. 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 average T/E ratios for the population in general tends close to 1:1.
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.
On September 20, 2007 Floyd Landis
was stripped of his title as winner of the Tour de France
, and was subjected to a two year ban from professional racing 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, more than double the 4:1 imposed limit (recently lowered from prior limits of 8:1 and 6:1). On August 1, 2006, media reports said that synthetic
testosterone had been detected in the A sample, using the carbon isotope
ratio test CIR. The presence of synthetic testosterone means that some of the testosterone in Landis’s body came from an external source and was not naturally produced by his own system. These results conflict with Landis's public speculation that it was a natural occurrence. Landis originally denied the charges, but in 2010 Landis admitted to doping during much of his career, but continued to adamantly deny taking testosterone that would have led to the positive test in the 2006 Tour de France.
Steroid
A steroid is a type of organic compound that contains a characteristic arrangement of four cycloalkane rings that are joined to each other. Examples of steroids include the dietary fat cholesterol, the sex hormones estradiol and testosterone, and the anti-inflammatory drug dexamethasone.The core...
, an inactive epimer
Epimer
In chemistry, epimers are diastereomers that differ in configuration of only one stereogenic center. Diastereomers are a class of stereoisomers that are non-superposable, non-mirror images of one another....
of the hormone testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
. 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, 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
Prostate
The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals....
. 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.
Epitestosterone and testosterone
It has been shown that exogenousExogenous
Exogenous refers to an action or object coming from outside a system. It is the opposite of endogenous, something generated from within the system....
administration of testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands...
does not affect levels of epitestosterone in the body. As a result, tests to determine the ratio of testosterone to epitestosterone in urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
are used to find athletes who are doping
Doping (sport)
The use of performance-enhancing drugs in sport is commonly referred to by the term "doping", particularly by those organizations that regulate competitions. The use of performance enhancing drugs is mostly done to improve athletic performance. This is why many sports ban the use of performance...
. 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 average T/E ratios for the population in general tends close to 1:1.
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
Mary Decker
Mary Slaney is an American former track athlete. During her career, she won gold medals in the 1500 meters and 3000 meters at the 1983 World Championships, and set 17 official and unofficial world records and 36 US national records.-Biography:Mary Decker was born in Bunnvale, Hunterdon County, New...
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.
On September 20, 2007 Floyd Landis
Floyd Landis
Floyd Landis is an American retired cyclist who after initially being awarded victory in the 2006 Tour de France was stripped of his title for a doping offense. He was an all-around rider, with special skills in climbing and time-trialing, and is also known to be a very fast descender.Landis...
was stripped of his title as winner of the Tour de France
2006 Tour de France
The 2006 Tour de France was the 93rd Tour de France, taking place from July 1 to July 23, 2006. It was won by Óscar Pereiro following the disqualification of apparent winner Floyd Landis....
, and was subjected to a two year ban from professional racing 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, more than double the 4:1 imposed limit (recently lowered from prior limits of 8:1 and 6:1). On August 1, 2006, media reports said that synthetic
Organic synthesis
Organic synthesis is a special branch of chemical synthesis and is concerned with the construction of organic compounds via organic reactions. Organic molecules can often contain a higher level of complexity compared to purely inorganic compounds, so the synthesis of organic compounds has...
testosterone had been detected in the A sample, using the carbon isotope
Isotope
Isotopes are variants of atoms of a particular chemical element, which have differing numbers of neutrons. Atoms of a particular element by definition must contain the same number of protons but may have a distinct number of neutrons which differs from atom to atom, without changing the designation...
ratio test CIR. The presence of synthetic testosterone means that some of the testosterone in Landis’s body came from an external source and was not naturally produced by his own system. These results conflict with Landis's public speculation that it was a natural occurrence. Landis originally denied the charges, but in 2010 Landis admitted to doping during much of his career, but continued to adamantly deny taking testosterone that would have led to the positive test in the 2006 Tour de France.