INCREASED BONE-RESORPTION IN PATIENTS WITH CROHNS-DISEASE

Background: Patients with Crohn's disease are at risk of osteoporosis and premature fracture, However, the pathophysiology underlying bone l oss remains poorly understood and the optimum treatment has not been e stablished. Aim: To investigate mechanisms of bone loss in Crohn's dis ease using biochemical markers of bone turnover, Methods: Bone mineral density was measured at the hip and spine using dual-energy X-ray abs orptiometry in 117 patients (48 male) with Crohn's disease, Bone turno ver was assessed by measuring serum osteocalcin (BGP), pro-collagen ca rboxy-terminal propeptide (PICP), bone specific alkaline phosphatase ( BALP) and urinary deoxypyridinoline (DPD); and compared to age-matched healthy controls (n = 28). Results: Bone mineral density was reduced (z-score < -1) in 48 (41%) patients with Crohn's disease, Mean values for bone formation markers in patients with Crohn's disease were all w ithin the normal reference range (BGP 8.92 (+/- 3.23) ng/mL (normal ra nge 3.4-10.0), BALP 17.6(+/- 12.6) U/L (normal range 11.6-43.3), PICP 95.1 (+/- 46.5) ng/mL (normal range 69-163)) and were not significantl y different to the control population. However, mean urinary DPD was s ignificantly higher in patients with Crohn's disease compared to healt hy controls (10.97 (+/- 9.22) nm DPD/mM creatinine vs. 5.02 (+/- 1.03) nM DPD/mM creatinine, difference in means = 5.95, 95% CI: -9.6 to -2. 3, P = 0.00001) and compared to the UK reference range DPD levels were increased in 74 (63%) patients. Conclusions: Bone resorption as evide nced by urinary DPD was frequently increased in patients with Crohn's disease and was significantly higher than in an age-matched control po pulation. The high levels of urinary DPD suggest increased bone collag en degradation may contribute to osteoporosis in patients with Crohn's disease. These results suggest anti-resorptive agents such as the bis phosphonates may be effective treatment for osteoporosis in Crohn's di sease.