Bone mineral density is reduced in patients with Crohn's disease but not in patients with ulcerative colitis: a population based study.

BACKGROUND Patients with inflammatory bowel disease are at risk of developing metabolic bone disease. AIMS To compare bone mineral density in patients with Crohn's disease with patients with ulcerative colitis and healthy subjects, and to evaluate possible risk factors for bone loss in inflammatory bowel disease. PATIENTS 60 patients with Crohn's disease, 60 with ulcerative colitis, and 60 healthy subjects were investigated. Each group consisted of 24 men and 36 women. METHODS Lumbar spine, femoral neck, and total body bone mineral density were measured by dual x ray absorptiometry (DXA), and Z scores were obtained by comparison with age and sex matched normal values. RESULTS Mean Z scores were significantly lower in patients with Crohn's disease compared with patients with ulcerative colitis and healthy subjects. Patients with ulcerative colitis had bone mineral densities similar to healthy subjects. Use of corticosteroids, body mass index (BMI), and sex were significant predictor variables for bone mineral density in Crohn's disease. In ulcerative colitis only body mass index and sex were of significant importance. Disease localisation and small bowel resections had no influence on bone mineral density in patients with Crohn's disease. CONCLUSIONS Patients with Crohn's disease have reduced bone mineral density. Several factors are probably involved, but the reduction is associated with corticosteroid therapy. When studying skeletal effects of inflammatory bowel disease, patients with Crohn's disease and those with ulcerative colitis should be evaluated separately.