EFFECTS OF DIFFERENT TYPES OF ORAL CONTRACEPTIVES ON PROTEIN-BOUND IODINE AND 125I-TRIIODOTHYRONINE UPTAKE ON SEPHADEX

The protein-bound iodine (PBI) and the uptake of 125I-triiodothyronine on Sephadex (T3S) were determined in 47 control subjects and in 277 women taking oral contraceptives. Mean PBI was increased and mean T3S was decreased in women taking combined or sequential drugs, while the mean 'free thyroxine index' was unchanged in all groups. PBI was increased in 41-43%, and T3S decreased in 85-88% of the women taking combined or sequential drags, while 96% of the PBI-determinations and 91% of the T3S-determinations were normal in those taking low doses of gestagens. Norethindrone (1-2 mg) counteracted the depressing effect of oestrogens on the T3S while chlormadinone acetate (3 mg) had no effect. © 1969 Informa UK Ltd All rights reserved: reproduction in whole or part not permitted.