Abstract
Endocrine responses in seven power athletes were investigated during a 12 week strength training period, when the athletes were taking high doses of andro genic-anabolic steroids, and during the 13 weeks fol lowing drug withdrawal. During the use of steroids significant decreases (P < 0.05 to 0.001) in the serum concentrations of thyroid stimulating hormone, thyrox ine, triidothyronine, free thyroxine, and thyroid hor mone-binding globulin (TBG) were found, whereas the value of triidothyronine uptake increased (P < 0.001). In relation to the changes in the thyroid function param eters measured, we suggest that the primary target of androgen action was TBG biosynthesis. In five of the seven subjects, serum concentrations of growth hor mone increased 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 (P < 0.001) in serum estradiol. Furthermore, there were major decreases in serum LH (P < 0.01) and FSH (P < 0.01) concentrations, and testicular tes tosterone 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. No consistent changes were found in the eight control athletes.
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