OSTEOPOROSIS AND DETERMINANTS OF BONE-DENSITY IN PATIENTS WITH CROHNS-DISEASE

Low bone mineral density (BMD) is common in patients with Crohn's dise ase; however, the pathogenesis of bone loss and risk factors for osteo porosis are not established. Our aim was to evaluate the clinical, die tary, and nutritional determinants of BMD in Crohn's disease. A cross- sectional analysis of 117 patients with Crohn's disease was undertaken . All patients underwent a clinical and dietary evaluation including a ssessment of nutritional state and life-style. BMD was measured at the hip and lumbar spine by dual-energy x-ray absorptiometry; and z score s obtained by comparison with age- and sex-matched normal values for t he healthy UK population. Multiple regression analysis was used to ass ess associations between BMD and potential risk factors, allowing for possible confounding variable's. Thirteen (11%) patients had osteoporo sis (z score < -2), with osteopenia (z score < -1, > -2) in a further 34 (29%). Patients with jejunal disease had significantly lower BMD at the spine (P = 0.03) and femoral neck (P = 0.02) than those with dise ase at other sites. Mean BMD was significantly lower at the hip of pat ients with previous bowel resection (diff in means = 0.53, 95% CI -0.9 7, -0.08, P = 0.02), but type of surgery was not significant. Active d isease menstrual history, diet, level of physical activity, and smokin g were not associated with low bone mass. At the lumbar spine, body we ight (P < 0.0001), male sex (P < 0.0001), and current prednisolone use (P < 0.02) were independently predictive of low bone mass. Body weigh t (P < 0.0001), male sex (P < 0.0001), and cumulative steroid dose (P = 0.02) were predictive at the femoral neck. The major determinants of BMD in Crohn's disease are body weight, current steroid use, and cumu lative steroid dose. Men with Crohn's disease are at greatest risk of osteoporosis, with jejunal involvement and previous bowel resection al so contributing to the low bone mineral density.