Endogenous Estrogen Levels and Its Relationship With Bone Mineral Density in Postmenopausal Women

A BAGUR; M BELOTTI; M.B. OLIVERI,; A LOPEZ CABANILLAS; D YANKELEVICH; F SAYEGH

POHENIX -ARIZONA -USA

Congreso; XXIII Congreso Anual de la ASBMR; 2001

Postmenopausal women whose serum estradiol levels are between 5-25 pg/ml would have higher bonemineral density (BMD) and a lower prevalence of vertebral deformities than women with lower serumestradiol levels and these salutary effects would be moderated by reduced bone turnover. The aim of thisstudy is to evaluate the effect of endogenous estrogens on BMD in healthy postmenopausal women. Uponcompletion, this cross sectional study will have included 100 healthy postmenopausal women from 55 to75 years of age. The BMD of L2-L4, Total Femur (TF) and Total Body (TB) are measured by DXA(Lunar Prodigy). The following bone markers are measured in serum: calcium, bone alkaline phosphatase(BAP) and crosslaps (CTX), and in urine calcium. Estradiol and estrona are measured with sensitiveassays that detect lower limit at 5 pg/ml. To date, 48 women have been included in the study. The generalcharacteristics of the population are as follows (Mean±DS): age 65.0±5.8 years, weight 63.2±9.7 kg,height 155±0.05 cm, BMI 26.2±4.2, onset of menopause 48.8±6.1 years, L2-L4: 0.99±0.02 g/cm2 (Zscore -0.2), TF 0.85±0.10 g/cm2 (Z score -0.02), TB 1.01±0.02 g/cm2 (Z score -0.2), BAP 74.7±18.7 UI/l(Normal values: 31-95 UI/l) and CTX 522.9±267.8 ng/l (Postmenopausal Normal values: 80-590 ng/ml) ,estradiol 8.5±5.7 pg/ml (Postmenopausal Normal values: up to 20 pg/ml), estrona 23.5±16.0 pg/ml(Normal values: 14-100 pg/ml).The 48 women were stratified into 4 groups according to their serumestradiol levels: 10 pg/ml and into 2 groups based on their serum estrona: 15 pg/ml. The results show nodifferences in BMD areas according to estradiol and estrona levels in these postmenopausal women(range L2-L4 from 1.02 to 0.98 g/cm2, TF from 0.84 to 0.89 g/cm2 and TB from 1.04 to 0.98g/cm2).Bone alkaline phosphatase was significantly higher in group >10 pg/ml (p< 0.02). Estradiol andestrona did not correlate with BMD and bone markers. Estradiol only correlated significantly with estrona(p<0.02). These preliminary results obtained with 48 post menopausal women show: 1- No associationbetween the low levels of estradiol and estrona determined using ultrasensitive assays and differences inBMD of L2-L4, Total Femur and Total Body. 2- The higher BAP levels observed in the group with thehighest estradiol levels (>10 pg/ml) might indicate a positive influence of estrogens on bone mass