C-telopeptides of type I collagen in postmenopausal women: An experience in a Tunisian Clinical Laboratory

Abstract

Aim: The purpose of study was to evaluate the interest of Ctelopeptides of type I collagen (CTX) in the diagnosis of osteoporosis in postmenopausal women and to define its cut-off value.
Methods: A transverse descriptive study enrolled postmenopausal women: 139 osteoporotic (G1) and 39 non osteoporotic (G2). The 2 groups were defined by bone density measurement. The following markers were measured: serum alkaline phosphatase (ALP), bone alkaline phosphatase (bone ALP), serum C-terminal telopeptide of type I collagen (CTX). Statistical analyses were performed using SPSS 10.5. The corresponding estimation of sensitivity and specificity of CTX have been presented as ‘receiver Operating Curve’ (ROC).
Results: There was no difference in the measurement of ALP and bone ALP in the 2 groups but CTX was statistically higher in G1 compared to G2 (p <0.001). The percentage of osteoporotic women (G1) with CTX values > 0.500 ng/ml was higher than that of non osteoporotic women (G2). We have established a ROC curve to find the cut-off value of CTX that enables the distinction between osteoporotic women with high level of bone remodelling, and non osteoporotic women. The cut-off value of CTX 0.55 pg/ml was the best; it associated best sensitivity and specificity.
Conclusion : The total increase and significance for CTX was greater in the group of osteoporotic women and appeared therefore to be a good bone turnover marker in the diagnosis of osteoporosis in comparison with ALP and bone ALP. The cut-off value of CTX 0.55 pg/ml may improve the sensitivity and specificity of prediction of future fractures.