Role of type I collagen C telopeptide, bone-specific alkaline phosphatase and osteocalcin in the assessment of bone status in postmenopausal women

To investigate the clinical role of the bone turnover markers type I collagen C telopeptide (CTX), osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) in the assessment of bone status in women with postmenopausal osteoporosis. Serum CTX (s-CTX), OC and BAP were measured in 200 healthy menopausal women at their initial visit and were correlated with spine and femur bone mineral density (BMD), determined on dual-energy X-ray absorptiometry. The relationship between biochemical markers of bone turnover and age, age at menopause, body mass index (BMI) and BMD was analyzed using linear correlation. A receiver operating characteristic (ROC) curve was constructed for each serum marker versus both femur and vertebral BMD. No correlation was found between serum levels of OC and BAP and vertebral or femur BMD. A statistically significant inverse correlation was found between s-CTX and BMD at spine and femur. S-CTX levels were higher in women with osteoporosis than in women with normal or moderately low (osteopenic) values of BMD. The sensitivity and specificity versus spine BMD were 73.9% and 41.6% for s-CTX, 40.4% and 80.6% for BAP, and 68.3% and 39% for OC, respectively. The sensitivity and specificity versus femur BMD were 76.9% and 40.4% for s-CTX, 23.8% and 88.3% for BAP, and 80.4% and 53.3% for OC, respectively. Determination of s-CTX, BAP and OC is of limited clinical value in the initial evaluation of bone status in menopausal women.