HUNTER HEATH III, M.D.; ROGER B. LEE, M.D.; RICHARD C. DIMOND, M.D.; LEONARD WARTOFSKY, M.D.
The effects of various doses of conjugated estrogens (Premarin®) on modern thyroid function tests were studied in 14 euthyroid menopausal women before and after 6 weeks of therapy with each of these daily doses: 0.625 mg, 1.25 mg, 2.5 mg, and, again, 0.625 mg. Serum thyroxine, triiodothyronine, thyroxine-binding globulin, and thyrotrophin were measured by radioimmunoassay, free thyroxine by dialysis, and triiodothyronine binding index by a conventional method. Increasing doses of conjugated estrogens led to stepwise elevations of thyroxine, triiodothyronine, thyroxine-binding globulin, and the binding index, with a threshold dose below 0.625 mg/day. The peak effect seemed to be between 1.25 and 2.5 mg/day. Free thyroxine and thyrotrophin concentrations did not change at any dose.
HEATH H, LEE RB, DIMOND RC, WARTOFSKY L. Conjugated Estrogen Therapy and Tests of Thyroid Function. Ann Intern Med. ;81:351–354. doi: 10.7326/0003-4819-81-3-351
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Published: Ann Intern Med. 1974;81(3):351-354.
Endocrine and Metabolism, Thyroid Disorders.
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