COMPARISON OF THE LONG-TERM EFFECTS OF ORAL ESTRIOL WITH THE EFFECTS OF CONJUGATED ESTROGEN, 1-ALPHA-HYDROXYVITAMIN D-3 AND CALCIUM LACTATEON VERTEBRAL BONE LOSS IN EARLY MENOPAUSAL WOMEN

We investigated the long-term effects of oral estriol (E-3) on bone mi neral density (BMD) at the lumbar spine and biochemical indices of bon e turnover iri early menopausal women. We studied 64 healthy early men opausal women who were treated for 24 months with 2.0 mg E-3 plus 2.5 mg medroxyprogesterone acetate daily (E-3 group, n = 15), 0.625 mg of conjugated estrogen plus 2.5 mg medroxyprogesterone acetate daily (CE group, n = 19), 1.0 mu g 1-alpha-hydroxyvitamin D-3 daily (D-3 group, n = 13), or 1.8 g calcium lactate containing 250 mg of elemental calci um daily (Ca group, n = 17). The BMD at the third lumbar vertebra was determined by quantitative computed tomography, and serum levels of os teocalcin (OC) and total alkaline phosphatase (Alp), as well as urinar y ratios of calcium-to-creatinine (Ca/Cr) and hydroxyproline-to-creati nine (Hyp/Cr), were evaluated at baseline and every 6 months. After 24 months of treatment, the BMD decreased significantly by 12 +/- 4.5% ( mean +/- S.E.) in the D-3 group and 14 +/- 2.5% in the Ca group, but n ot in the E-3 group (-4.1 +/- 4.8% from baseline) and in the CE group (-0.9 +/- 3.2% from baseline). The serum levels of Alp and OC decrease d or remained unchanged in the E-3 and CE groups, but increased in the D-3 and Ca groups. The urinary Ca/Cr was decreased in the E-3 and CE groups, but not in the D-3 and Ca groups. The urinary Hyp/Cr decreased in the CE group, was unchanged in the E-3 and D-3 groups, and increas ed in the Ca group. Uterine bleeding occurred less frequently in the E -3 than in the CE group (2.4 +/- 4.2 versus 13.1 +/- 14.8 days/person per year, P < 0.001). The bone-preserving effect of 2.0 mg of oral E-3 was comparable to that of 0.625 mg of conjugated estrogen and was sup erior to that of 1.0 mu g 1-alpha-hydroxyvitamin D-3 and 1.8 g Ca. Our findings suggest that a reduction in bone turnover in the E-3 group m ay have contributed to the preservation of bone. (C) 1997 Elsevier Sci ence Ireland Ltd.