Estriol Guards Against the Disease-Producing Side Effects of Estradiol

OBJECTIVE: We investigated the long-term effects of oral estriol (E(3)) on serum levels of total cholesterol (t-Cho), high-density lipoprotein cholesterol (HDL-Cho), low-density lipoprotein cholesterol (LDL-Cho), and triglycerides in early menopausal women.

METHODS: We studied 67 healthy early menopausal women who were treated for 48 months with 2.0 mg of E(3) plus 2.5 mg of medroxyprogesterone acetate daily (E(3) group, n=21), 0.625 mg of conjugated estrogen plus 2.5 mg of medroxyprogesterone acetate daily (CE group, n=19), or 1.0 microg of 1alpha-hydroxyvitamin D(3) daily or 1.8 g of calcium lactate containing 250 mg of elemental calcium daily (control group, n=27). The serum levels of t-Cho, HDL-Cho, LDL-Cho, and triglycerides were evaluated at baseline and every 6 months.

RESULTS: After 48 months of treatment, the t-Cho decreased significantly by 4.3+/-2.1% (mean+/-SE) from baseline in the E(3) group, did not change in the CE group (-1.9+/-2.1%), and significantly increased (5.4+/-3.4%) in the control group. The HDL-Cho significantly increased in the CE group (10.7+/-2.4%), but not in the E(3) group (3.8+/-3.3%) or in the control group (-3.6+/-3. 0%). The LDL-Cho significantly decreased in the CE group (-11.4+/-4. 0%), did not change in the E(3) group (-5.2+/-3.6%), and significantly increased in the control group (11.8+/-6.3%). The triglyceride level decreased significantly in the E(3) group (-6. 7+/-4.9%), whereas it significantly increased in the CE group (17. 6+/-11.4%), and did not change in the control group (6.1+/-6.4%).

CONCLUSIONS: Oral E(3) prevented a postmenopausal rise in the t-Cho. Oral estriol did not induce the hypertriglyceridemia that was seen after treatment with conjugated estrogen. Oral E(3) may be a useful alternative therapy in women with hypertriglyceridemia and in women who are reluctant to continue conventional hormone replacement therapy because of uterine bleeding.