THE SHORT-TERM EFFECTS OF CONJUGATED ESTROGEN ON BONE TURNOVER IN OLDER WOMEN

Estrogen replacement therapy (ERT) prevents bone loss and fracture in early postmenopausal women, but its benefit for women over 70 yr of ag e has not been determined. We have examined the effect of a short cour se of ERT on biochemical markers of bone turnover in older women. Elev en women (mean age, 77 yr) were given conjugated estrogen (Premarin; 0 .625 mg/day) for 6 weeks. Biochemical markers were measured on serum a nd urine collected at baseline (two samples), after 5 and 6 weeks of E RT, and 5 and 6 weeks post-ERT. Markers of bone formation were osteoca lcin, bone alkaline phosphatase, and type I procollagen peptide. Marke rs of bone resorption were total urinary hydroxyproline, total and fre e pyridinoline and deoxypyridinoline cross-links, type I collagen cros s-linked N-telopeptides, and serum C-terminal cross-linked telopeptide . Data were analyzed by repeated measures multivariate analysis of var iance to estimate the overall effect of ERT on the biochemical markers . Markers of bone resorption decreased during ERT and returned to base line after ERT (P < 0.05). Markers of bone formation declined less dur ing ERT and continued to decline after ERT (P < 0.05). We conclude tha t ERT reduces bone turnover in older women and that markers of bone tu rnover may be useful in assessing the response to treatment in this ag e group.