Evaluation of bone resorption: a common problem during impaired mobility

Osteoporosis, the result of an imbalance between bone resorption and bone formation, is a potential problem for the individual with a spinal cord injury because of the immobility commonly associated with this impairment. This study was performed to determine the diagnostic value of a new assay for urinary Pyridinium crosslink (UPyr). Assays were performed on 62 first morning voided and 50 24-hour urine specimens from clients in a bone health clinic. Higher than normal levels of UPyr were observed in females with osteoporosis. UPyr correlated well with urinary hydroxyproline (r = 0.429, p = 0.005; conversely, there was an inverse relationship between bone density and UPyr (r = -0.489, p = 0.01), positive correlation (r = 0.43, p = 0.011) between the 24-hour UPyr and a serum marker of bone resorption. The study confirms that UPyr has the ability to identify states of high bone resorption. This assay should be a welcome addition to the bone health assessment of individuals with risk factors such as impaired physical mobility.