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Evaluation of urinary N-telopeptide of type I collagen measurements in the management of osteoporosis in clinical practice



We measured urinary N-telopeptide of type I collagen (U-NTX) to monitor response to bisphosphonates for osteoporosis. Decrease in U-NTX was associated with increase in spine bone density. A lesser response in U-NTX was more likely in those with secondary osteoporosis or with poor compliance. U-NTX may be a useful early indicator of treatment non-compliance or secondary osteoporosis.


This study aims to determine the utility of the bone resorption marker, U-NTX, in the clinical setting, to monitor the response to bisphosphonate therapy (alendronate and risedronate) for osteoporosis.


A retrospective evaluation of data collected as part of the bone turnover marker monitoring service in the Metabolic Bone Centre, Sheffield, UK. Treatment compliance, underlying causes of osteoporosis, change in U-NTX/creatinine (Cr) at 4 months and change in spine and hip bone mineral density (BMD) by dual-energy X-ray absorptiometry were recorded. Treatment response was defined as either a change in U-NTX/Cr greater than a pre-defined least significant change (LSC) of 54 % or to within the lower half of a pre-defined pre-menopausal reference interval (≤30 nM BCE/mmol Cr).


A greater decrease in U-NTX/Cr at 4 months was associated with a greater increase in spine BMD at 18 months (r = −0.33; P < 0.0001, Pearson’s correlation). The mean U-NTX/Cr at 4 months was higher in patients with secondary osteoporosis compared with those with primary osteoporosis (P < 0.01, ANOVA). A lesser response in U-NTX/Cr increased the likelihood of secondary osteoporosis or poor treatment compliance (P = 0.04, Fisher’s exact test). A lack of response in U-NTX/Cr to within the lower half of the reference interval was a better indicator of secondary osteoporosis and treatment non-compliance than a change in U-NTX/Cr greater than LSC.


Treatment monitoring using U-NTX/Cr has a place in clinical practice for the early identification of non-compliance or presence of secondary osteoporosis.

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IB was assisted by the clinical staff at the Metabolic Bone Centre and research support staff at the NIHR Musculoskeletal Biomedical Research Unit, Sheffield. IB’s studentship was funded by Inverness Medical, UK. This work was supported by the NIHR-funded Sheffield Musculoskeletal Biomedical Research Unit. Authors would like to acknowledge the assistance of the Editorial Board of the Musculoskeletal Biomedical Research Unit for preparing and reviewing the manuscript. The views expressed in this publication are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health.

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Correspondence to R. Eastell.

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Baxter, I., Rogers, A., Eastell, R. et al. Evaluation of urinary N-telopeptide of type I collagen measurements in the management of osteoporosis in clinical practice. Osteoporos Int 24, 941–947 (2013).

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