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

Aim:  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. Methods:  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. Results:  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. Conclusions:  Determination of s-CTX, BAP and OC is of limited clinical value in the initial evaluation of bone status in menopausal women