Progesterone has no effect on serum thyroxine binding globulin concentration in men

To examine the possible effect of progesterone on circulating T4-binding globulin (TBG) in men, RIA measurements of plasma TBG and T4 levels were made before and after weekly administration of 500 mg medroxyprogesterone acetate, im, to men being treated for paraphilia (sexual deviation syndromes). No change in the mean pretreatment plasma TBG concentration was found after 7-29 days [21.5 ± 1.2 (±SEM) to 22.0 ± 0.9 Mg/ml; n = 14) or 381-415 days (23.0 ± 2.5 to 23.1 ± 2.5 fig/ml; n = 5) of medroxyprogesterone treatment. Similarly, the mean pretreatment plasma T₄ concentration was unaltered by acute (9.7 ± 0.6 to 9.7 ± 0.4 Mg/dl; n = 14) or chronic (11.1 ± 1.2 to 11.4 ± 1.0 Mg/dl; n = 5) medroxyprogesterone therapy. We conclude that progestational agents alone do not modify circulating TBG or total T₄ concentrations in men.