The Usefulness of Biochemical Markers of Bone turnover for Bone Mineral Density in Early Postmenopausal Women Treated with Hormone Replacement or Calcium Supplementation

Bai, Kwang Bum

Abstract

OBJECTIVE
To identify the effectiveness of bone turnover indexes for bone loss or gain in early postmenopausal women. METHOD: This study was performed in 240 menopausal women(mean age, 50 yr), who were randomized to hormone replacement therapy(HRT) or calcium supplementation(CS, 500mg/day) for 1yr. Urinary N-telopeptide(NTx) and osteocalcin(OC), as well as spine and femoral neck bone mineral density(BMD) were measured at baseline and 1, 3, 6, 12 months after treatment.
RESULTS
Women receiving HRT(n=110) showed a significant increase in spine BMD(+2.6%; P<0.0001) and hip BMD(+1.1%; P<0.05) compared to women receiving CS, who showed a decline at both sites (-1.0%; P<0.01). Both markers showed time dependent decreases in women receiving HRT(P<0.001) and no change in women receiving calcium alone. When baseline indexes of turnover were divided by quartile, there was a significantly greater increase in BMD among those with the highest NTx, OC levels compared to that in those with the lowest NTx, OC levles(P<0.05). When subjects receiving HRT were compared by their positive or negative skeletal response at 1yr and their baseline turnover marker, initial NTx values were significantly higher in those that gained bone than in those that lost bone (P<0.001). Calcium supplementation women in the highest quartile for NTx at baseline had significantly greater decreases in spine BMD than subjects with the lowest NTx values(P<0.005).
CONCLUSIONS
For early postmenopausal women there are differential responses of biochemical markers to HRT and calcium supplementation. Baseline urinary NTx and serum osteocalcin were good predictors of change in spine BMD after 1yr of either HRT or calcium supplementation. It is concluded that markers of bone formation and resorption can be used clinically to predict future BMD in early postmenopausal women.