Variability of serum estrogens among postmenopausal women treated with the same transdermal estrogen therapy and the effect on androgens and sex hormone binding globulin.Fertil Steril. 2003 Mar; 79(3):534-42.FS
To examine the variability of serum estrogens in response to transdermal estrogen replacement therapy (ET), and to determine the effects on androgens and sex hormone binding globulin (SHBG).
Randomized, double-blind, placebo-controlled study.
Two groups of postmenopausal women:  21 women not on ET enrolled and 17 completed the study;  19 women on continuous transdermal ET enrolled and 13 completed the study.
Women not on ET were administered a placebo patch or a newly initiated estrogen patch, then crossed over to the alternate treatment. Serum samples were obtained at baseline and the subsequent 3 days from the placebo and new-patch groups and from a separate group of women receiving continuous estrogen patch treatment.
MAIN OUTCOME MEASURE(S)
Estradiol (E(2)), estrone, estrone sulfate, T, dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), androstenedione, free androgen index, and SHBG.
There was considerable intrapatient and interpatient variability in the estrogen response to identical treatment doses, with E(2) values differing between women as much as 138 pg/mL and E(2) increases above baseline differing as much as 90 pg/mL. Continuous treatment increased SHBG and decreased androstenedione levels; however, levels of T, DHEA, DHEAS, and free androgen index did not change.
There is great variability of estrogen in response to transdermal ET, but minimal effect on circulating androgens.