Metabolic Effects of Oral Versus Transdermal Estrogen in Growth Hormone-Treated Girls with Turner Syndrome

Abstract

Abstract Background: Transdermal (TD) estrogen is often preferred over the oral route in postmenopausal and GH-deficient women taking estrogen, but this has not been studied in detail in girls. Objective: Our objective was to study the metabolic effects of oral vs. TD estrogen in GH-treated girls with Turner syndrome. Design and Methods: Eleven girls with Turner syndrome, mean age 13.4 ± 0.5 (se) yr, on GH for at least 6 months were recruited. Studies included [13C]leucine and d5-glycerol infusions, indirect calorimetry, dual-emission x-ray absorptiometry, and hormone and substrate measurements. They received, in random order, 17β-estradiol orally (0.5, 1, and 2 mg for 2 wk each) and TD (0.025, 0.0375, and 0.05 mg for 2 wk each), and studies were repeated after each 6-wk course with 4 wk washout in between. Results: Rates of whole-body protein turnover, oxidation and synthesis, lipolysis, lipid and carbohydrate oxidation, and resting energy expenditure were unaffected by either form of estrogen; nor were lipids, insulin, and fibrinogen concentrations affected. Plasma IGF-I concentrations did not change clinically significantly with either form of estrogen, despite higher estrogen concentrations after oral estrogen. Estradiol concentrations did not correlate with any variables measured. Conclusions: In GH-treated girls with Turner syndrome, neither oral nor TD estrogen adversely affected rates of protein turnover, lipolysis, and lipid oxidation rates or plasma lipids, fibrinogen, or fasting insulin concentrations. There was no clinically significant change in IGF-I concentrations after either form of estrogen. In aggregate, these data suggest that the route of delivery of estrogen does not adversely affect these metabolic effects of GH in young girls with Turner syndrome.