To estimate the physiologically normal metabolic fluxes of androgenic steroid hormones in peripheral tissues and in the liver. These fluxes are modulated by physiological effects (e.g. physical activity) but also by illicit administration of synthetic androgenic steroids, normally testosterone. Depending on the route of administration (transdermal or oral), testosterone doping should be detectable by abnormally high rates of either peripheral or hepatic androgen fluxes.