Testosterone epitestosterone ratio

Aguilera R, Chapman TE, Starcevic B, Hatton CK, and Catlin DH (2001) Performance characteristics of a carbon isotope ratio method for detecting doping with testosterone based on urine diols Controls and athletes with elevated testosterone/epitestosterone ratios. Clinical Chemistry 47 292-300. 

In terms of doping, hCG can be abused to artificially increase plasma testosterone levels. The assumed reasons for this include (a) the stimulation of the testicular testosterone production to counteract the anabolic steroid-induced reduced testis size, and (b) the attempt to mask anabolic steroid misuse being detected by altered urinary steroid profiles or suspicious testosterone /epitestosterone ratios (T/E, see Chapter 6). Consequently, hCG has been prohibited in sports for male athletes since 1987, and the first arbitrary threshold levels of 25 international units (lU) per L of urine were corrected to In 2005, hCG was... 

An epimer of testosterone, epitestosterone (17a-hydro-xylated testosterone), is produced by the testes and excreted as such in the urine in amounts approximately equal to that of testosterone(T epiT 1 1). Epitestosterone is biologically inactive, but it is not a metabolite, and is believed to be produced only by the gonads thus, it is used as a gonadal steroid marker. In women, the ratio of T to epiT is also normally 1 1. Urinary T epiT is useful in monitoring abuse of anabolic steroids by athletes because the ratio increases when any exogenous testosterone derivative is used. 

Bosy, T.Z., Moore, K.A., and Poklis, A. (1998) The effect of oral dehydroepiandrosterone (DHLA) on the urine testosterone/epitestosterone (T/E) ratio in human male volunteers. Journal of Analytical Toxicology, 22, 455-459. 

Karila, T, Kosunen, V., Leinonen, A., et al. (1996) High doses of alcohol increase urinary testosterone-to-epitestosterone ratio in females. Journal of Chromatography B, Biomedical Applications, 687,109-116. 

In the human female, whose pituitary hormones may be suppressed by the use of oral contraceptives, the ratio of testosterone to creatinine in urine may be used. Alternatively, a method suitable for both males and females is to measure the ratio of total testosterone to epitestosterone using gas chromatography—mass spectrometry. In this method, the bis(trimethylsilyl) derivative is formed and the intensity of the molecular ions at m/z 432, under electron impact conditions for both of the steroid derivatives, is used to determine the ratio (M. Donike and J. Zimmermann, J. Chromat, 1980, 202, 483-486). The internationally accepted limit for the ratio is currently 6. 

Gatlin DH> Cowan DA, de la Torre R, Donike M, Fraisse D, Oftebro H, et al. Urinary testosterone (T) to epitestosterone (E) ratios by GC/MS. I. Initial comparison of uncorrected T/E in six interna-tional laboratories. J Mass Spectrom 1996 31 397-402. 

Buiarelli et al. (2004) extended the above analytical approach to many more related steroids when they published a method for the direct analysis of 15 urinary anabolic steroids in a single run, namely T, epitestosterone, dehydroepiandrosterone (DHEA), androsterone, etiocholanolone, their sulfates and their glucuronides (Figure 2,2), They extracted 2 mL of human urine by solid-phase extraction with methanol elution and reconstituted the residue in aqueous methanol in the presence of deuterated internal standards (da-epitestosterone glucuronide, [16,16,17-"H3 testosterone sulfate and [16,16,17-2H3]testosterone), then monitored, for example, mJz. 289-97 and 109 for T and epitestosterone, miz 367-97 for their sulfates, and m/z 463-113 and 287 for their glucuronides. The method does not achieve quantitation, but it allows the estimation of ratios, which makes it possible to monitor the urinary steroid profile, which is useful for monitoring the abuse of anabolic steroids. 

Finally, researchers have perfected techniques of using carbon isotope ratios to identify unnatural molecules of otherwise natural compounds. This ability has led to the detection of synthetic testosterone in several athletes. In 2006, American Floyd Landis took over where Lance Armstrong left off, winning the Tour de France after the former champion s retirement. Unfortunately, after stage 17, Landis tested positive for an elevated ratio of testosterone to its precursor epitestosterone. Subsequent tests of carbon isotope ratios showed that the samples contained synthetic testosterone. 

The most infamous case is that of American cyclist Floyd Landis. The story begins on July 20, 2006, when Landis won section 17 of the Tour de France. He was required to undergo a doping test following the race. The level of testosterone in urine is determined by a method called GC-MS (Gas Chromatography— Mass Spectrometry), and is often referred to as the T/E test. Here, T means testosterone, whereas E stands for epitestosterone, which is a variant of the hormone that occurs in the body but has none of its effects. In most humans, the T/E ratio is about 1. The... 

Testosterone has an inactive isomer called epitestosterone, which differs in only one stereogenic center - the OH group. Testosterone is the S-isomer and epitestosterone is the i -isomer. In most people, they occur in an approximate 1 1 ratio however, epitestosterone has no anabolic effects. 

Testers in sport look at the relative amounts of testosterone and epitestosterone. In 1982, the International Olympic Commission (IOC) decided that, from 1982, a 6 1 ratio would result in immediate disqualihcation. The rule now says that if the ratio is above 4 1, additional samples must be tested. 

In cases of suspected administration of anabolic steroids such as testosterone (Section 4-7), two approaches are used. The first compares the ratio of testosterone (T) to its stereoisomer, epitestosterone (E identical to T except that the hydroxy group on the five-membered ring is down instead of up ). E and T occur naturally in humans in roughly equal amounts, but E, unlike T, does not enhance performance. Taking synthetic T alters the T E ratio and is easily detected. Therefore, some athletes have taken synthetic T and E together, to maintain a T E ratio within normal limits. Mass spectrometry identifies these situations, because of a quirk of biology Synthetic steroids are made from plant-derived precursors, which have a slightly lower content (relative to C) than do steroids bio synthesized naturally in the human body. The differences are quite small (parts per thousand)... 

Falk, O., Palonek, E., and Bjorkhem, I. (1988) Effect of ethanol on the ratio between testosterone and epitestosterone in urine. Clinical Chemistry, 34,1462-1464. 

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