Received on March 28, 2005
Accepted on September 23, 2005

Endocrinology and Metabolism

Serum Concentrations of Cross-Linked N-Telopeptides of Type I Collagen: New Marker for Bone Resorption in Hemodialysis Patients

¹ Shirasagi Hospital, Osaka, Japan
² Department of Metabolism, Endocrinology and Molecular Medicine, Osaka City University Graduate School of Medicine, Osaka, Japan

^* To whom correspondence should be addressed. E-mail: inaba-m{at}med.osaka-cu.ac.jp.

Methods: Serum concentrations of NTX, C-terminal telopeptide of type I collagen (-CTX), pyridinoline (PYD), and deoxypyridinoline (DPD) were determined as bone resorption markers, and those of bone-specific alkaline phosphatase (BAP) and intact osteocalcin (OC) as bone formation markers, in 113 male HD patients (mean age, 59.5 years; mean HD duration, 67.7 months). Each patient's bone mineral density (BMD) in the distal third of the radius was measured twice, with a 2-year interval between measurements, by dual-energy x-ray absorptiometry.

Results: Serum NTX correlated significantly with -CTX, PYD, DPD, BAP, and intact OC. NTX, as well as -CTX, PYD, DPD, BAP, and intact OC, correlated significantly with BMD at the time of measurement. NTX, -CTX, and DPD correlated significantly with the annual change in BMD during the 2-year period thereafter, in contrast to PYD, BAP, and intact OC. Patients in the highest quartile of serum NTX concentrations showed the fastest rate of bone loss. The sensitivity and specificity for detecting rapid bone loss were 48% and 83%, respectively, for serum NTX.

Conclusion: Serum NTX may provide a clinically relevant serum assay to estimate bone turnover in HD patients.