Bone mineral content in patients with Crohn's disease. A longitudinal study in patients with bowel resections.

Background: Low bone mineral content (BMC) has been reported in patients with inflammatory bowel disease. The aim of the present study was to measure BMC in patients with Crohn's disease.

Methods: BMC was monitored for a mean period of 5.5 years in 108 patients. The patients were divided into two groups: group A, patients with the colon preserved; group B, patients with a resected colon. The mean length of the resected small intestine was 90 cm.

Results: The BMC of the lumbar spine expressed as Z-score ((actual value-mean)/s) was significantly reduced: mean Z-score for group A, -0.51, P < 0.05; group B, -0.80, P < 0.001. The BMC of the femoral neck was significantly reduced: mean Z-score for group A, -1.24, P < 0.001; group B, -1.23, P < 0.001. A Z-score below -2.0 of spine or femoral neck BMC was found in 10% and 23% of the patients, respectively. The BMC of the femoral neck decreased significantly in both groups during the study period (group A, -2.2%, P < 0.001; group B, -1.21%, P < 0.05). The BMC of the lumbar spine did not change. There was an inverse correlation between the initial Z-score and the rate of change in BMC (P < 0.05). We found no correlation between Z-score or change in BMC and period of prednisolone treatment. Moreover, there was no correlation between the length of the resected small intestine and BMC or annual percentage change in BMC.

Conclusion: At inclusion the BMC of the spine and femoral neck was low in patients with Crohn's disease. During the study significant bone loss was only demonstrated in the femoral neck. BMC or rate of change in BMC was not related to treatment with steroids or length of the resected small intestine.