Dihydrotestosterone (DHT) (referred to as androstanolone or stanolone when used medically) can also be used in place of testosterone as an androgen. The availability of DHT is limited; it is not available in the United States or Canada, for instance, but it is available in certain European countries, including the United Kingdom , France , Spain , Belgium , Italy , and Luxembourg .  DHT is available in formulations including topical gel, buccal or sublingual tablets, and as esters in oil for intramuscular injection.  Relative to testosterone, and similarly to many synthetic AAS, DHT has the potential advantages of not being locally potentiated in so-called androgenic tissues that express 5α-reductase (as DHT is already 5α-reduced) and of not being aromatized into an estrogen (it is not a substrate for aromatase).
In testing for hGH, technicians rely on a sophisticated understanding of how the body reacts when you inject higher concentrations of the hormone — other forms of the hormone start to drop. So, testers look at the ratio between hGH and these other derivatives to detect foul play. Too large a gap between these concentrations is a red flag that the user may be boosting with injected hGH. To further improve their chances of detecting doped levels of the hormone, Butch says it may soon be possible to look for the molecular fingerprint that hGH leaves on other compounds, even after the actual hormone has long been cleared from the body. “We can go from a 36-hour window for detecting hGH to a couple of weeks,” he says.