[Effect of the male sex hormone and its 5 alpha-reduced metabolites on the function of the thyroid in vivo and in vitro].

The administration of testosterone propionate, dihydrotestosterone and androstandiol to male rats was followed by different changes in thyroid function. Testosterone propionate exerted a stimulating effect, whereas its metabolites induced marked depression of thyroid functional activity in the experiments in vivo. In vitro both sex hormones and 5-alpha-reduced metabolites inhibited radioactive iodine absorption by rat thyroid slices and human thyrotoxic struma. The data demonstrate that testosterone may produce a direct effect on the thyroid without the hypophysis.