NTx (N Telopeptide of Collagen)

Clinical Use: Urine NTx can be used to monitor response to antiresorptive therapy, confirm patient compliance and assess efficacy of new therapies in patients with metabolic bone disease such as osteoporosis, Paget’s disease, primary hyperparathyroidism and metastatic bone disease
Background: NTx is a marker of bone resorption, based on detecting fragments of type 1 collagen released during osteoclastic resorption and then excreted in urine. Type 1 collagen is formed in bone from the combination of two collagen polypeptides containing hydroxylated lysine and proline residues. Collagen fibrils are subsequently stabilized by the formation of pyridinium cross links, pyridinoline and deoxypyridinoline, in the telopeptide regions. The NTx assay measures N-telopeptide-linked pyridinoline and deoxypyridinoline residues in urine from the breakdown of type 1 collagen.
Reference Ranges: Male: 16 – 90 nM BCE/ mmol
Female pre-menopausal: 15 – 114 nM BCE/mmol creatinine
Female post-menopause: 29 – 148 nM BCE/ mmol CreatinineCreatinine Single measurements are of limited value. The least significant change between samples taken at 3 month intervals is +/ 50%. Suppression of NTx by more than 50% from baseline is expected after bisphosphonate therapy as early as 3 months, but routine follow-up may be left to 6 months post therapy.

NTx levels may remain elevated for up to 6-9 months following healing of bone fractures.

Paediatric samples and young adults: Specific age-related reference ranges are not available but NTx levels are significantly higher in children and in young adults.

Associated Diseases:
Patient Preparation: None required
Specimen Requirements: Ideally a second morning void urine sample
Turnaround Time: Assay is performed on a daily basis
Additional Information:
Referred Test: Referred test
Location: Northern General Hospital NHS Trust