Long-term treatment with raloxifene, but not bisphosphonates, reduces circulating sclerostin levels in postmenopausal women

Summary We determined whether suppression of sclerostin levels by estrogen treatment was mediated by anti-resorptive effect. Raloxifene, but not bisphosphonates, suppressed circulating sclerostin concentration, suggesting that sclerostin may mediate the action of estrogen on bone metabolism, independently of their anti-resorptive effects. Introduction Circulating sclerostin concentrations are higher in postmenopausal than in premenopausal women, and estrogen treatment suppresses sclerostin levels in both men and women. We determined whether anti-resorptives may suppress the circulating sclerostin levels. Methods We conducted a retrospective observational study. Eighty postmenopausal women were treated with raloxifene for 19.4 ± 7.7 months ( n = 16), bisphosphonates for 19.2 ± 6.7 months ( n = 32), or were untreated ( n = 32) for 17.1 ± 4.6 months. Plasma sclerostin concentrations were measured before and after treatment. Results Plasma sclerostin levels after treatment were significantly lower in the raloxifene than in the control group (55.8 ± 23.4 pmol/l vs. 92.1 ± 50.4 pmol/l, p = 0.046), but were similar between the bisphosphonate and control groups. Relative to baseline, raloxifene treatment markedly reduced plasma sclerostin concentration (−40.7 ± 22.8%, p