Here's some info on the testing for testosterone abuse:
What is a T:E Ratio?
Testosterone (T) = male sex hormone that is both anabolic (increased protein synthesis in tissues) and androgenic (development and maintenance of male characteristics) Epitestosterone (E) =an inactive form of testerone that is a naturally occuring in the body
Most men have a ratio of T to E of 1:1. Studies have shown that in male athletes the mean ratio was 1.15:1 and for those in the top 95th percentile 3.71:1(1). The World Anti-Doping Agency allows a 4:1 ratio while the NCAA and many state athletic commisions allow a 6:1 ratio.
The 4:1 ratio was chosen so that there is 95% accuracy for the test to determine that the T:E ratio of the athlete tested is artificially high. I found mention of a study showing that a ratio of ~6:1 can be found in men in the 99thpercentile. I was not able to find the specific study on PubMed but did find several references to it. The 6:1 ratio has been the standard for several large athletic organizations going back 30 years or more.
T:E is used in PED monitoring because externally added testosterone will NOT convert to epitestosterone (2). An athlete that adds testosterone to his/her body will see a rise in their T while the E remains the same, creating an irregularity in the T:E ratio. For those that are interested in reading more on this please check out this link (http://scienceblogs.com/purepedantry/2006/07/27/floyd-landis-and-testosterone/)
1. Trout GJ, Soo S, Kelly, K; Longitudinal Variability of T/E Ratios in Austrailian Athletes. Recent advances in doping analysis (10). Sport und Buch Strauss, Koln, (2002) 261-265