Ingestion of androgenic-anabolic steroids induces mild thyroidal impairment in male body builders.

Self-administration of very high doses of androgenic anabolic steroids is common use in power athletes because of their favorable effect on performance. Since androgenic steroids decrease serum T4-binding globulin (TBG) concentrations dramatically, we were interested in the effects of this procedure on thyroid function: we performed TRH tests (200 micrograms Relefact, i.v.), with blood withdrawal before and for 180 min after injection, for determination, using RIA kits, of serum concentrations of total and free T4, total T3, TSH, and TBG in 13 young (20-29 yr old) male body builders with clinically normal thyroid glands, who were all in the same state of training. Five of these athletes admitted taking androgenic anabolic steroids at an average total dose of 1.2 g/week for at least 6 weeks before the tests. TBG, total T4, and total T3 were significantly (P < 0.001) decreased, whereas basal TSH and free T4 were not significantly different from the values of the other 8 without androgenic steroids. The maximum TSH increase after TRH administration (mean +/- SE, 16 -/+ 6 vs. 9 -/+ 4 mU/L; P < 0.05) was relatively increased, whereas the T3 response to TRH (0.61 -/+ 0.10 vs. 1.13 -/+ 0.13 nmol/L; P < 0.05) was relatively decreased in the group receiving androgens. The 5 patients taking androgens had significantly greater weight (114 vs. 90 kg; P < 0.01) and higher total cholesterol levels (6.3 -/+ 1.3 vs. 3.8 -/+ 0.3 mmol/L; P < 0.05) together with very low high density lipoprotein cholesterol levels (0.20 -/+ 0.03 vs. 1.03 -/+ 0.10; P < 0.001) than the controls. PRL levels were normal and similar in both groups. We conclude from our results that high dose androgenic anabolic steroid administration leads to a relative impairment (within the normal range) of thyroid function. Whether this is due to a direct thyroid hormone release (or synthesis?)-blocking effect of these steroids needs further investigation.