C-telopeptide

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.

C-telopeptide 是I型胶原交联C端肽^[1]。在骨吸收过程中，C-telopeptide 被组织蛋白酶K降解，从而从氨基（N）末端裂解出血清s-NTX，从羧基（C）末端裂解出C-telopeptide。s-NTX和C-telopeptide进入循环系统，其浓度能够反映正在进行的骨吸收水平^[2]。C-telopeptide是骨吸收的参考标志物，可以加深对骨转换标志物（BTM）临床应用价值的理解^[2-3]。