Validity of the Testosterone / Epitestosterone Ratio Technique in detecting the use of Exogenous Testosterone by Athletes
By Dr Simon Davis B.Sc., Ph.D.
Summary
Although the testosterone (T) / epitestosterone (E) ratio test has widely been used since its inception, the increasing number of false positive results, combined with a growing body of scientific evidence, has cast doubt on the accuracy and precision of this technique.
A 1996 inter-laboratory study by members of IOC accredited laboratories (including Professor Cowan of Kings College Laboratory) emphasized this point when reporting their inability to accurately analyze the T/E ratio of standard urines. Although internal precision was good, variations between the participating laboratories were statistically significant, with reported values differing by up to 20.1%.
The inter-laboratory variability could result in the report of a ratio > 6 to 1 which, if analyzed by a different laboratory, would be reported as < 6 to 1. The authors explained this variation as being due to the “inherently complex” nature of the test and “urine-laboratory interaction”. The observed variation was not improved by the absence of any international standards, the use of which is mandatory in other areas of analytical science. To the best of my knowledge, international standards are still not used as part of the T/E analytical protocol.
It would appear, therefore, that results reported by IOC accredited laboratories do not always accurately reflect the true T and E content of analyzed samples.
Not only is the analytical validity of the test in question, but the premise that a ratio of 6/1 infers a doping offence is also unsafe. Numerous papers, many authored by employees of IOC accredited laboratories, report observing T/E levels greater than 6/1 in individuals who have not committed a doping offence. If the number of individuals with naturally high ratios equaled the most conservative estimates, they could still account for the majority of positive results reported by the UK Sports Council.
As recently as September 1997, Dick Schultz, the Executive Director of the United States Olympic Committee stated that if no satisfactory testing method could be found then the IOC should strike T from its banned list.
Due to inadequacies in the current test, the IOC will shortly change the way T abuse is detected. The new procedure will use isotope ratio mass spectrometry (GC/C/IRMS). This technique can discern between naturally high T and T administered exogenously. This means athletes need no longer worry about false positives from bacterial degradation, ethanol consumption, naturally high T concentrations or pathologically low E concentrations. This technique has been used in two Olympic games and the apparatus is widely available in IOC accredited laboratories. As GC/C/IRMS is current best technology, it is reasonable to assume it should be used in preference to the flawed T/E ratio test.
The inability of the T/E test to detect naturally high ratios, combined with poor analytical accuracy make any reports of exogenous T abuse scientifically unsound. In short it is not possible to determine if a doping offence has been committed solely on the basis of a urinary T/E ratio greater than 6/1.
The Effect of Alcohol Consumption on the Urinary Testosterone / Epitestosterone Ratio
By Dr Simon Davis B.Sc., Ph.D.
Summary
Intoxicating beverages contain a number of different forms of alcohol, the major constituent of which is ethanol. When a beverage is consumed the ethanol content passes through the stomach wall and digestive tract into the blood stream. Once the ethanol enters circulation it begins to alter the bodies’ biochemistry. One such reaction is to differentially increase the rates of testosterone (T) and epitestosterone (E) metabolism. The overall effect of this reaction is to increase the ratio of T to E excreted in the urine.
It has been reported that ethanol consumption can increase urinary T/E ratios by 30% - 277% in healthy individuals. Observed changes in plasma T/E ratios can occur with the consumption of less than 2 pints of lager. The ingestion of ethanol by an individual will increase the T/E ratio observed in a urine sample.
It follows that if the effect of ethanol on T/E ratios is calculated relative to urinary E concentrations, it can be seen that increases in the ratio are exponential as E concentrations decrease. Individuals with naturally low E concentrations could, therefore, experience increases in T/E ratios of ? 940% greater than increases experienced in an individual with normal E concentrations. Calculations estimate that in individuals with low urinary E concentration, ratios of 17 to 1 or higher could have resulted from ethanol consumption without any administration of exogenous T.
The current T/E ratio test
as performed by Kings College Laboratory and approved by
the UK Sports, the IWF and IOC cannot discriminate between
a 13 to 1 T/E ratio resulting from ethanol ingestion or a
13 to 1 ratio resulting from endogenous T administration.