Body composition by dual-energy X-ray absorptiometry in patients with Crohn's disease.

BACKGROUND: To study body composition at the whole-body level in patients with Crohn's disease and a history of intestinal resection compared with healthy controls, we performed a cross-sectional study using dual-energy X-ray absorptiometry (DXA).
METHODS: Thirty-one patients, 13 men and 18 women, were included. They had a history of Crohn's disease for a mean period of 20 years (range, 4-45 years). All patients had undergone intestinal resections. The colon had been resected in 24 patients, and the mean length of the resected small intestine was 97 cm (range, 0-305 cm). At the time of investigation the Crohn's disease had been in remission for at least 24 months. Patients presented with significantly increased faecal volume and faecal fat excretion. A group of 69 women and 19 men were investigated with DXA and used as reference group. The fat-free mass (FFM), fat mass (FM), percentage fat mass (FM%), and total body mineral content (TBMC) were measured by DXA, and the results were expressed as a z-score.
RESULTS: The mean z-score of the body mass index (BMI) was significantly reduced to -0.35 (P=0.036). The FFM was significantly reduced with a mean z-score of -1.74 (P=0.0001). The FM was unchanged (z-score, 0.12; P=0.42). However, FM expressed as percentage of body weight was significantly increased, with a z-score of 0.88 (P=0.001). The TBMC was significantly decreased, with a mean z-score of -1.42 (P=0.0001). There was positive direct correlation between the BMI and TBMC z-scores. There was no correlation between malabsorption and body composition variables.
CONCLUSION: Patients with clinically quiescent Crohn's disease showed significant changes in body composition, with low BMI, significant loss of FFM, and unchanged FM. However, when expressed as percentage of body weight, FM was significantly increased. The TBMC was significantly reduced.