N-terminal telopeptide

The N-terminal telopeptide (NTX), also known as amino-terminal collagen crosslinks, is the N-terminal telopeptide of fibrillar collagens such as collagen type I and type II. It is used as a biomarker to measure the rate of bone turnover. NTX can be measured in the urine (uNTX) or serum (serum NTX).[1] The peptide consists of eight amino acids with the sequence YDEKSTGG.[2]

N-terminal telopeptide
Names
Other names
NTX; N-terminal crosslinked telopeptides of collagen 1; Collagen alpha-1(IX) chain
Identifiers
3D model (JSmol)
  • [C@@H](NC([C@@H](NC([C@@H](NC([C@H](CC1=CC=C(O)C=C1)N)=O)CC(O)=O)=O)CCC(O)=O)=O)(C(N[C@H](C(N[C@H](C(NCC(NCC(O)=O)=O)=O)[C@@H](C)O)=O)CO)=O)CCCCN
Properties
C35H53N9O16
Molar mass 855.856 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Usefulness of NTX as a biomarker

Evaluating an individual's rate of bone turnover, termed bone remodeling, directly may be important in assessing his or her potential nonsurgical treatment response as well as evaluating his or her risk of developing complications during healing following surgical intervention. To determine an individual's rate of bone turnover, numerous biomarkers are available in the body fluids that can be correlated to this rate, and one such biomarker is NTX.[1]

However, while NTX does fluctuate in a very sensitive manner in line with bone resorption patterns, they are not very specific, in that they may vary spontaneously without physiologic intervention. For example, NTX levels may drop by 50% from day to day with no treatment,[3] thus, making NTX levels unconvincing evidence of treatment effect.[4]

Conversely, the serum CTX biomarker, described in 2000 by Rosen, appears to be a much more effective and valuable indicator of bone resorption rate.[4]

See also

References
  1. Iba, Kousuke; Takada, Junichi; Hatakeyama, Naoko; Ozasa, Yasuhiro; Wada, Takuro; Yamashita, Toshihiko (9 October 2008). "Changes in urinary NTX levels in patients with primary osteoporosis undergoing long-term bisphosphonate treatment". Journal of Orthopaedic Science. 13 (5): 438–441. doi:10.1007/s00776-008-1265-z. PMID 18843458.
  2. "N-terminal telopeptide". MarkerDB.
  3. Rosen, HN; Moses, AC; Garber, J; Iloputaife, ID; Ross, DS; Lee, SL; Greenspan, SL (February 2000). "Serum CTX: a new marker of bone resorption that shows treatment effect more often than other markers because of low coefficient of variability and large changes with bisphosphonate therapy". Calcified Tissue International. 66 (2): 100–3. doi:10.1007/pl00005830. PMID 10652955.
  4. Rosen, HN; Moses, AC; Garber, J; Ross, DS; Lee, SL; Greenspan, SL (November 1998). "Utility of biochemical markers of bone turnover in the follow-up of patients treated with bisphosphonates". Calcified Tissue International. 63 (5): 363–8. doi:10.1007/s002239900541. PMID 9799818.
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