Bone mineral density and body composition in ulcerative colitis: a six-year follow-up

Reduced bone mineral density (BMD) has been reported in ulcerative colitis (UC), but there are no data concerning body composition (fat and lean mass) in such patients. We used whole body dual-energy X-ray absorptiometry (Hologic QDR 1000 W) at baseline and after 6 years of follow-up to study bone density, and fat and lean mass in 43 outpatients with mild UC (21 men, mean age 36 years, range 21-57 years, and 22 women, mean age 35 years, range 23-45 years at baseline; disease extent: 2 proctitis, 18 proctosigmoiditis, 8 left colitis, 5 substantial colitis, 10 pancolitis; mean disease duration 8 years, range 2-18 years; no hospitalization; few relapses during the follow-up) and 111 healthy volunteers matched by sex, age and body mass index. There were 5 drop-outs. We observed no significant difference in BMD, or fat and lean mass between the male patients and controls at baseline or after 6 years. The total lean mass (Z-score = -3.2, p = 0.001) and trunk lean mass (Z-score = -2.01, p = 0.03) of the female patients were lower than those of the controls at baseline, whereas their limb lean mass was higher at both the beginning and the end of the study (Z-score = 2.14, p = 0.03; Z-score = 2.8, p = 0.004, respectively). At baseline there was a significant negative correlation between lifetime steroid intake (enteral and parenteral) and lumbar spine BMD, obtained as whole body subregion (r = -0.53, p = 0.0006). After 6 years there was a significant negative correlation in women between whole body and lumbar spine BMD and both steroid intake (r = -0.53, p = 0.01; and r = -0.62, p = 0.003) and the number of relapses (r = -0.49, p = 0.02; and r = -0.44, p = 0.05). Mild UC thus does not represent a risk factor for osteopenia per se. The differences in lean mass between the female patients and controls do not seem to be clinically relevant.