What are the best tests for detecting anabolic steroid use in athletes?—Jeffrey B. Rosen, MD, Coral Gables, Fla.

The World Anti-Doping Agency has an excellent and informative Web site (www.wada-ama.org/en/) dedicated broadly to education of sports organizations, athletes, smaller anti-doping agencies, and the media. This Web site contains information regarding banned substances and lists of necessary medications for which exemptions might be obtained by an individual athlete. Determining whether or not an athlete is using anabolic steroids may start with a history revealing competition in a sport where the drugs would be thought to provide performance enhancement. Physical exam might reveal testicular atrophy in men, acne, or balding or hirsutism in women. General laboratory testing might show an elevated hemoglobin or hematocrit. The most sophisticated and arguably the most accurate test for exogenous testosterone use involves measuring the ratio of carbon 13 (13C) to carbon 12 (12C) in the urinary testosterone metabolites of an athlete. Most anabolic steroids are derived from plants, which have a lower ratio of 13C to 12C compared with endogenous testosterone; hence the urinary testosterone metabolites will have a low 13C: 12C ratio (Clin Chem. 2001;47: 292-300). Other tests involve comparing urinary ratios of testosterone glucuronide to epitestosterone glucuronide (Clin Chem. 1992;38:1685-1686). The normal ratio is 1-3:1; with use of exogenous testosterone, this ratio rises. The World Anti-Doping Agency considers a ratio greater than 4:1 to be consistent with doping.—Christopher Ruser, MD