Hormone replacement with estradiol: conventional oral doses result in excessive exposure to estrone.

Authors: Friel PN, Hinchcliffe C, Wright JV.

Publication Year: 2005

Citation: Altern Med Rev 2005;10(1):36-41.

Studies have shown increased breast cancer risk in women with high levels of estradiol and estrone in their urine.  This study therefore investigated urinary estrone and estradiol concentrations in 35 women taking between 0.025 and 2.0 mg/day oral estradiol.  Urinary levels of both estrogens increased as the estradiol dosage increased.  At doses of 0.25 mg/day or higher, urine estrone levels were higher than seen in non-pregnant premenopausal women, while at doses of 0.5 mg/day or higher, urine estradiol was higher than in non-pregnant premenopausal women.  Estradiol given at a dose of 1 mg/day resulted in excessive serum estrone levels.  To minimize breast cancer risk, the authors recommend oral estradiol doses no higher than 0.25 mg/day.