Background: Postmenopausal osteoporosis (PMO) is a debilitating disease induced by estrogen deficiency characterized by bone loss and bone micro-architecture degradation contributing to fragility fractures. Osteopontin (OPN) has been found to be involved in bone turnover by activating the resorption process.
Objectives: This study aim to evaluate the relationship between serum OPN levels and bone mineral density (BMD) for identification of female individuals at high risk of osteoporotic fractures.
Methods: A total of eighty eight postmenopausal women (PMW) were recruited in this study. Densitometry results addressed cases of the study into 3 groups: thirty with osteoporosis, thirty with osteopenia and twenty eight PMW without complications as a control group. Serum OPN was measured by using Enzyme-Linked immunosorbent assay (ELISA) kits and BMD was obtained at lumbar spine and femoral neck by dual-energy X-ray absorptiometry (DEXA).
Results: Osteopontin levels were significantly higher in osteoporotic group compared to osteopenic and control groups (P ˂ 0.001). Negative correlation was found between BMD and OPN in osteoporotic group. By using the Receiver Operating Characteristic (ROC) curve, the cutoff level of ≥ 10.294 ng/mL for OPN was chosen for suggesting osteoporosis which yield a sensitivity of 66.67 % and specificity of 96.43 %.  Also, there were a significant increase in serum ALP levels in osteoporotic and osteopenic groups compared to control group while serum Ca failed to show a significant difference between the studied groups. In addition, serum TAC showed a significant decrease in osteoporotic group compared to control group.
Conclusion: These findings suggest that the circulating OPN might play role in the pathophysiology of PMO. Its blood concentration can be used as a sensitive monitoring indicator for the early detection of osteoporosis independently of BMD.