C-telopeptide is the cross-linked C-telopeptide of type I collagen[1]. During bone resorption, C-telopeptide is degraded by cathepsin K to cleave serum s-NTX from the amino (N)-terminal end and C-telopeptide from the carboxy (C)-terminal end. s-NTX and C-telopeptide make their way into the circulation, where their concentration provides information regarding the level of ongoing bone resorption[2]. C-telopeptide is a reference marker of bone resorption, which enhances understanding of the clinical utility of bone turnover markers (BTM)[2-3].
References:
[1] Rathnayake H, Lekamwasam S, Wickramatilake C, De Zoysa E, Lenora J. Age-related trends and reference intervals of cross-linked C-telopeptide of type I collagen and procollagen type I N-propeptide from a reference population of Sri Lankan adult women. Arch Osteoporos. 2021;16(1):164.
[2] Bauer D, Krege J, Lane N, et al. National Bone Health Alliance Bone Turnover Marker Project: current practices and the need for US harmonization, standardization, and common reference ranges. Osteoporos Int. 2012;23(10):2425-2433.
[3] Comparison of two automated assays of BTM (CTX and P1NP) and reference intervals in a Danish population.