Urinary excretion of type I collagen cross-linked N-telopeptide and serum bone-specific alkaline phosphatase analysis to determine the correlation of age and back-pain related changes in elderly women

We evaluated bone turnover using biochemical markers in 273 women over 60 years of age with suspected osteoporosis. Their age range was 60–96 years, with an average of 72.7 years. Patients with disorders that might affect bone metabolism were excluded. Those complaining of back pain within 6 months before or after examination were assigned to the back-pain group. Serum bone-specific alkaline phosphatase (BAP) was measured as a bone formation marker, and the urinary N-terminal telopeptide of type I collagen (NTX) was measured as a bone resorption marker. Both BAP and NTX levels increased in individuals over 60 years of age; moreover, these markers were significantly higher in subjects aged over 80 years. Among elderly patients, both BAP and NTX levels were significantly higher in those with back pain than in those without, and in a similar way were observed to increase in parallel with age from the 60-year point. We found that both NTX and BAP increased with aging, and that the increase in these bone turnover markers was closely related to back pain. We also showed that NTX and BAP levels increased significantly in women over 80 years, and specifically in patients with back pain.