PubMed1983
To determine the influence of the route of administration on the hormonal and lipemic responses to 17 beta-estradiol, 50 postmenopausal women were studied before and after various regimens of replacement therapy. The effects on plasma lipids and lipoproteins and on estrone and estradiol levels of the oral administration of micronized estradiol or estradiol valerate (2 mg/24 hours) were compared to those of percutaneously administered estradiol (3 mg/24 hours). These treatments were given during two cycles of 3 weeks separated by a 1-week interval. Circulating levels of estradiol and estrone increased significantly (p less than 0.05) in all groups while follicle-stimulating hormone levels decreased significantly. The posttreatment estradiol/estrone ratio was significantly (p less than 0.05) greater in the parenteral group (0.8 +/- 0.1) than in both oral estrogen groups (0.3 +/- 0.1 and 0.4 +/- 0.1, respectively). Oral administration of estradiol resulted in a significant increase in triglycerides (20% to 44%, p less than 0.05) and very low-density lipoprotein (VLDL) triglycerides (30% to 40%, p less than 0.05) and a decrease in low-density lipoprotein cholesterol (14% to 17%, p less than 0.05). In contrast, despite a substantial increase in serum estrogen levels, percutaneous estradiol induced a significant decrease in triglyceride (from 0.78 +/- 0.04 to 0.67 +/- 0.05 mmol/L, p less than 0.001) and VLDL triglyceride (from 0.44 +/- 0.16 to 0.35 +/- 0.12 mmol/L p less than 0.05) levels and no significant change in cholesterol levels. The increases of high-density lipoprotein cholesterol levels observed in the three groups were not significant. These data indicate that the route of administration modulates the metabolic and hormonal responses to estrogen therapy.