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. 1974;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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