Serum sclerostin levels in men with idiopathic osteoporosis

Objective: Sclerostin inhibits osteoblast differentiation and bone formation. If aberrant sclerostin action is involved in less efficient bone acquisition in men with idiopathic low bone mass, this might be reflected in higher serum sclerostin levels. Methods: In 116 men with idiopathic osteoporosis (<= 65 years old), 40 of their sons and healthy controls, areal bone parameters were measured using dual-energy X-ray absorptiometry, and volumetric and geometric bone parameters were measured using peripheral quantitative computed tomography. Serum analytes were measured using immunoassays and estradiol (E-2) levels using liquid chromatography-tandem mass spectrometry. Results: Men with idiopathic low bone mass had lower levels of sclerostin than the controls (0.54 +/- 0.17 vs 0.66 +/- 0.23 ng/ml; P < 0.001). In both groups, sclerostin levels were strongly associated with age; when adjusting for age, no associations with anthropometrics were observed (P > 0.14). In multivariate analyses, sclerostin levels displayed a positive association with whole-body bone mineral content (BMC) and areal BMD (aBMD), as well as with trabecular and cortical volumetric bone mineral density (vBMD) at the tibia in the probands. No clear associations were observed in the control group, neither were sclerostin levels associated with BMC at the radius or lumbar spine (all P > 0.11). Testosterone, but not E-2, was inversely related to sclerostin levels in the probands. No difference in sclerostin levels was found in their sons when compared with their controls. Conclusion: Lower rather than higher serum sclerostin levels in the probands with idiopathic low bone mass suggest that aberrant sclerostin secretion is not involved in the pathogenesis of low bone mass in these subjects. European Journal of Endocrinology 168 615-620