Body composition measured by dual-energy X-ray absorptiometry in patients who have undergone small-intestinal resection

BACKGROUND: Patients who have undergone resection of the small intestine have lower body weight than do healthy persons. It remains unclear whether it is the body fat mass or the lean tissue mass that is reduced. OBJECTIVE: We compared body-composition values in patients who had undergone small-intestinal resection with reference values obtained in healthy volunteers, and we studied the relation between body-composition estimates and the net intestinal absorption of energy. DESIGN: In a cross-sectional study, we included 20 men and 24 women who had undergone small-intestinal resection and had malabsorption of energy > 2000 kJ/d. Diagnoses were Crohn disease (n = 37) and other conditions (n = 7). Body composition was estimated by dual-energy X-ray absorptiometry, and data were compared with those from a reference group of 173 healthy volunteers. Energy absorption was measured during 48-h balance studies by using bomb calorimetry, and individual values were expressed relative to the basal metabolic rate. RESULTS: Body weight and body mass index in patients were significantly (P < 0.05) lower than the reference values. Fat mass was 6.4 kg (30%) lower (95% CI: -8.8, -3.9 kg), but lean tissue mass was only slightly and insignificantly lower (1.5 kg, or 3.3%; 95% CI: -3.7, 0.60 kg). Weight, body mass index, and body-composition estimates by dual-energy X-ray absorptiometry did not correlate significantly with the net energy absorption relative to the basal metabolic rate, expressed as a percentage. CONCLUSIONS: Patients who had undergone small-intestinal resection had significantly lower body weights and body mass indexes than did healthy persons, and they had significant changes in body composition, mainly decreased body fat mass.