Abstract

Endocrine responses in seven power athletes were investigated during a 12 week strength training period, when the athletes were taking high doses of androgenic-anabolic steroids, and during the 13 weeks following drug withdrawal. During the use of steroids significant decreases in the serum concentrations of thyroid stimulating hormone, thyroxine, triidothyronine, free thyroxine, and thyroid hormone-binding globulin (TBG) were found, whereas the value of triidothyronine uptake increased. In relation to the changes in the tyhroid function parameters measured, we suggest that the primary target of androgen action was TBG biosynthesis. In five of the seven subjects, serum concentrations of growth hormone incraesed at some point of the study 5 to 60-fold. Because of the use of exogenous testosterone, serum testosterone concentration tended to increase. This increase was associated with a corresponding increase in serum estradiol. Furthermore, there were major decreases in serum LH and FSH concentrations, and testicular testosterone production was therefore decreased. This was characterized by a very low serum testosterone concentration (5.1 +/- 1.8 nmol/l) 4 weeks following drug withdrawal. Cessation of drug use resulted in return of all the variables measured to the initial values, except for serum testosterone, which was at a low level (14.6 +/- 8.8 nmol/l) 9 weeks after drug withdrawal, indicating prolonged impairment of testicular endocrine function. Verf.-Referat