Postmenopausal osteoporosis is characterised by increased bone turnover, a negative balance (resorption>formation) and increased fracture risk. Bisphosphonate treatment reduces bone turnover and fracture risk but their effect on bone balance is yet to be fully investigated. We have compared the effects of bisphosphonates on turnover and balance in postmenopausal women with osteoporosis using a T-score bone marker method. 165 postmenopausal women (hip and spine BMD T-score ≤-2.5 or <-1 with a prior fracture) were recruited, mean age 67years. They were provided with calcium and vitamin D supplements and randomised to receive ibandronate (n=55, 150mg/month), alendronate (n=54, 70mg/week) or risedronate (n=56, 35mg/week). A fasting serum sample was collected at baseline and weeks 1,2,4,12,13 and 48 on treatment. The control group were 200 healthy premenopausal women receiving no treatments. PINP and CTX were measured using the iSYS-IDS analyser. Values were log10-transformed and normalised. The T-scores for PINP and CTX value were calculated for each postmenopausal woman using the mean and standard deviation values from the premenopausal group. By week 48 bisphosphonates reduced mean levels of turnover to -2.1SD units (95% CI:-2.322,-1.848) below the mean of the premenopausal women p<0.001. Mean levels of balance were positive (0.3SD units, 95% CI: 0.145, 0.559), p<0.01. Mean levels (95% CI) of balance and turnover for each bisphosphonate are shown in the table. By week 48 turnover decreased, p<0.001 and balance was more positive with alendronate only, p<0.01. In postmenopausal osteoporosis treatment with bisphosphonates improves bone balance by making it more positive and reduces bone turnover, relative to healthy premenopausal women. Bisphosphonates have differing effects on turnover and balance.
Disclosure: Dr N Peel has received speakers honoraria and funding from Warner-Chilcott. Dr Walsh has received speakers honoraria. Professor McCloskey has received funding from Warner-Chilcott. Professor Eastell has received funding from Warner-Chilcott and the NIHR and consultancy funding from Warner-Chilcott, Roche, Immunodiagnostic Systems and Merck. This was funded by Warner-Chilcott.