Circulating sclerostin levels and markers of bone turnover in Chinese-American and white women.

CONTEXT

Chinese-American women have bone microarchitectural features that confer greater bone stiffness compared to white women, but the physiology underlying these findings has not been investigated.

OBJECTIVE

The purpose of the study was to assess racial differences in serum sclerostin and bone turnover markers (BTMs), and to explore their associations with each other, volumetric bone mineral density (BMD), and bone microarchitecture in Chinese-American and white women.

DESIGN AND SETTING

We conducted a cross-sectional study at a university hospital.

PARTICIPANTS

We studied 138 women.

RESULTS

Serum osteocalcin was 19-28% lower in pre- and postmenopausal Chinese-American vs white women, respectively (both P < .01). C-Terminal telopeptide of type I collagen (CTX) level was 18-22% lower in pre- and postmenopausal Chinese-American vs white women (both P < .05). Pre- vs postmenopausal differences in osteocalcin and CTX were greater in white vs Chinese-American women. Sclerostin levels were similar in both races, but BTMs were differentially associated with sclerostin by race and menopausal status. BTMs were not correlated with sclerostin in Chinese-Americans. CTX and bone-specific alkaline phosphatase were positively associated with sclerostin (r = 0.353, r = 0.458; both P < .05) in white premenopausal women. In contrast, in postmenopausal white women, the associations of sclerostin with amino-terminal propeptide of type I procollagen, isoform 5b of tartrate-resistant acid phosphatase, and CTX were negative (all P < .05). Adjusting for covariates, sclerostin was positively associated with areal BMD in both races.

CONCLUSIONS

Lower BTMs in Chinese-American women and greater age-related differences in BTMs among white women provide a physiological framework to account for racial differences in BMD, microarchitecture, and fracture.