The influence of beta-adrenoceptor blocking agents on plasma thyroxine and triiodothyronine.
The effect of the beta-adrenoceptor blocking agent propranolol on plasma levels of thyroxine and triiodothyronine was studied in eleven hyperthyroid patients and in six hypothyroid patients on L-thyroxine substitution therapy. In all patients a decrease in plasma-triiodothyronine was found. The per cent decrease of plasma-triiodothyronine was the same in both groups. Plasma levels of thyroxine and thyrotropin increased in the hypothyroid patients, but remained constant in the hyperthyroid subjects. The decrease in plasma-triiodothyronine during propranolol medication is most likely caused by an inhibition of the peripheral conversion of thyroxine into triiodothyronine.
D000328:Adult; D000368:Aged; D000526:Alprenolol / Q000627:therapeutic use; D005260:Female; D006042:Goiter / Q000097:blood; D006801:Humans; D006980:Hyperthyroidism / Q000097:blood / Q000188:drug therapy; D007037:Hypothyroidism / Q000097:blood; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011433:Propranolol; D013972:Thyrotropin / Q000097:blood; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
D014284:Triiodothyronine; D000526:Alprenolol; D013972:Thyrotropin; D011433:Propranolol; D013974:Thyroxine