NEW YORK, May 08 (Reuters) -- Men who abuse anabolic steroids in an attempt to bulk up their muscles may end up shortening their life span, a new study in mice suggests. More than half of mice treated with steroids died by age 20 months -- about two thirds of their normal life span -- compared with just 12% of mice not given the drugs.
The male mice were given steroids in doses similar to those taken by humans who abuse the drugs, according to lead study author Franklin Bronson, of the Institute of Reproductive Biology at the University of Texas in Austin.
"The numbers, kinds, and relative doses of steroids to which our mice were exposed are quite like the numbers, kinds and relative doses of steroids to which athletes and body builders expose themselves," Bronson reported in the current issue of Medicine and Science in Sports and Exercise, the official journal of the American College of Sports Medicine.
The mice were given steroids 5 to 20 times their maintenance level, or the normal amount needed to maintain the testes, while human athletes typically take 10 to 40 times their maintenance level. About 52% of mice on high doses of steroids were dead by age 20 months, as were 35% of those on low doses. Only 12% of mice not given any medication died by age 20 months. Mice have an average life span of 30 months.
"Autopsy of the steroid-treated mice typically revealed tumors in the liver or kidney, other kinds of damage to these two organs, broadly invasive lymphosarcomas (a type of cancer), or heart damage, and usually more than one of these conditions," Bronson noted.
However, the mice were also given the drug for a longer period of time than it would be taken by most humans drug abusers. The rodents took four different anabolic steroids -- testosterone, testosterone cypionate, methyltestosterone, and norethandrolone -- for six months, or one-fifth their life span.
"This is undoubtedly longer than the duration to which most athletes and body builders expose themselves," the authors wrote. "Constant exposure over this period of time, without periodic washout periods, is also atypical of human use. Given all of these comparisons, we are probably only safe in concluding that the exposure parameters used in this experiment may be generalized for extreme steroid abusers."
The most important finding is that steroid use causes a wide variety of health effects that do not appear until long after steroid exposure, the authors noted. Steroid abuse did not become common until the 1970s, and combining several different drugs, or "stacking" did not become common until the 1980s, according to the report.
"Thus, the delayed effects of steroid abuse seen here in mice and the consequent dramatic effect on life span may ultimately prove to be a concern for athletes and body builders abusing steroids," Bronson concluded.
SOURCE: Medicine and Science in Sports and Exercise (1997;29:615-619)
