Comparison of the Impact of Transdermal Versus Oral Estrogens on Biliary Markers of Gallstone Formation in Postmenopausal Women

Abstract

This prospective, randomized, double blind, parallel study was undertaken to elucidate further the potential mechanisms through which estrogens could promote the formation of cholesterol gallstones and to compare the impact of nonoral (transdermal) and oral estrogens on serum, hepatic, and biliary markers of estrogen action. Ninety-seven postmenopausal women were randomized to receive either transdermal estradiol (E2; 0.1 mg every 3.5 days; n = 48) or oral conjugated equine estrogens (1.25 mg every day; n = 49) for 8 weeks. Blood samples were drawn, and bile samples were obtained by cholecystokinin-stimulated duodenal drainage before and after 8 weeks of estrogen administration. The main outcome measures included serum FSH, LH, E2, estrone, estrone sulfate, sex hormone-binding globulin, lipid profiles, biliary cholesterol saturation index, cholesterol nucleation time, presence of cholesterol crystals in bile, as well as biliary arachidonate, PGE2, and mucous glycoproteins. Estrogens administered by both r...