Serum and urine markers of bone metabolism during the year after hip fracture

OBJECTIVE: As part of a larger study to describe indices of recovery during the year after hip fracture, the current prospective study investigated lo ngitudinal changes in serum and urine markers of bone metabolism for the ye ar after hip fracture and related them to bone mineral density (BMD). DESIGN: A representative subset of participants provided serum and urine sa mples and had bone density measured at 3, 10, 60, 180, and 365 days postfra cture. SETTING: Two Baltimore hospitals. PARTICIPANTS: The subjects were 205 community-dwelling, white women age 65 and older with fresh proximal femur fractures. MEASUREMENTS: Samples were assayed for specific bone-related proteins and b one turnover markers, including serum osteocalcin (OC), procollagen type 1 carboxy-terminal extension peptide (PICP), bone-specific alkaline phosphata se (BAP), and urinary deoxypyridinoline (DPD) cross-links. Selected hormona l regulators of bone metabolism, including parathyroid hormone (PTH), calci tonin (CT), 1,25-dihydroxy vitamin D, (1,25 (OH)(2)D), and estrone (E-1) we re measured from serum samples. Repeated measures analyses were used to eva luate postfracture changes in each of the markers. RESULTS: BAP, OC, and PICP were most active during the early postfracture p eriod (3-60 days). BAP and OC remained elevated at 365 days compared with 3 days. DPD rose 48% from 3 days to 60 days, but this difference was not sta tistically significant. PTH and 1,25 (OH)(2)D increased steadily and signif icantly from 3 to 365 days. E-1 was highest at baseline and decreased at ea ch time point, whereas CT showed no significant changes. When subjects were stratified into high-, medium-, and low-BMD groups based on their measurem ent at 3 days, both osteoclastic and osteoblastic markers in the low-BMD gr oup displayed exaggerated and different patterns over time compared with th e other groups. CONCLUSION: Currently, the standard treatment of care for hip fractures sti ll results in high morbidity and mortality and failure to regain prefractur e quality of life. Gaining an understanding of bone cell activity in these patients after hip fracture, derived by measuring markers longitudinally du ring recovery, provides a baseline by which to measure the effectiveness of new interventions to improve recovery from hip fracture.