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May 4, 1984

Estrogen Dosage-Reply

Author Affiliations

Vanderbilt University Medical Center Nashville, Tenn

JAMA. 1984;251(17):2210. doi:10.1001/jama.1984.03340410022021

In Reply.—  Dr Hustead's perceptive comments on the relative potencies of conjugated estrogen and ethinyl estradiol are appreciated. While previous reports had suggested that 25 to 50 μg of ethinyl estradiol was protective against osteoporosis,1 these dosages were arbitrarily chosen. Mandel et al2 recently reported that 10 μg of ethinyl estradiol is approximately equivalent to 1.25 mg of conjugated estrogens on the basis of both hepatic and nonhepatic measurements, suggesting that ethinyl estradiol is far more potent than previously believed. Bolton et al3 found that 20 μg of ethinyl estradiol is equivalent to 1.25 mg of conjugated estrogen in the suppression of luteinizing hormone. However, Rudel and Kincl4 concluded that conjugated estrogen at a dose of 1.25 mg daily is more potent than 20 μg of ethinyl estradiol when compared on the basis of endometrial proliferation, vaginal cytology, and cervical mucus ferning. Therefore, while 5 to

Gallagher JC, Nordin DEC:  Effects of estrogen and progesterone therapy on calcium metabolism in postmenopausal women .  Front Horm Res 1975;3:153.
Mandel FP, Geola FL, Lu JKH, et al:  Biologic effects of various doses of ethinyl estradiol in postmenopausal women .  Obstet Gynecol 1982;59:673.
Bolton CH, Ellwood M, Hartog M, et al:  Comparison of the effects of ethinyl oestradiol and conjugated equine oestrogens in oophorectomized women .  Clin Endocrinol 1975;4:131.Crossref
Rudel HW, Kincl FA:  The biology of antifertility steroids .  Acta Endocrinol 1966;5( (suppl) ):105.