Bone turnover markers for osteoporosis status assessment at baseline in postmenopausal Pakistani females

Objective: To assess bone turnover status in osteopenic and osteoporotic postmenopausal females. Study Design: Cross-sectional analytical study. Place and Duration of Study: The Aga Khan University Hospital, Karachi, from January to December 2013. Methodology: A cross-sectional study was conducted on 203 postmenopausal females undergoing bone mineral density testing (BMD) by DXA scan. Patients with clinical history of any disorder or medications affecting bone turnover were excluded. Bone turnover was assessed with osteocalcin and b-CTx. Data was analyzed by SPSS version 19. Results: Mean age of the participants was 54 ±4.66 years with a mean BMI of 28.7 ±5.5 kg/m². Mean b-CTx (0.28 ±0.24 ng/ml) and osteocalcin (21.5 ±10.6 ng/ml) levels were within the normal reference range. Subjects were grouped into normal (26.6%), osteopenic (44.8%), and osteoporotic (28.6%) based on the t-scores. Serum levels of osteocalcin and b-CTx between normal, osteopenic, and osteoporotic groups were not significantly different. b-CTx was negatively and significantly associated with only lumber spine BMD (r = -0.13, p=0.04). Positive association (< 0.0001) was noted between both markers in normal, osteopenic, and osteoporotic females. However, association of these markers with BMD in the 3 groups were not found. Multivariate linear regression showed a positive and significant effect of BMI on BMD (b = 0.332, p= < 0.0001). b-CTx had negative but significant effect on BMD (b = -0.155, p= 0.018) of postmenopausal women. Conclusion: Association between baseline levels of BTM and rate of bone loss is variable and site dependent. b-CTx correlates better with BMD. However, role of osteocalcin in postmenopausal osteoporosis is uncertain and needs further investigation.