Colonic transit time in long-term dialysis patients

Background. Constipation is a frequent health concern for long-term dialysis patients. The increased incidence of constipation in long-term dialysis patients is based mainly on self-reported data. Our aim is to investigate this problem objectively by using colonic transit time in long-term hemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD) patients. Methods: Segmental and total colonic transit time studies measured by means of radiopaque markers were conducted in 56 HD patients, 63 CAPD patients, and 25 healthy control subjects. Segmental colonic transit times were calculated separately for 3 segments of the colon (right, left, and rectosigmoid) and total transit time, which was the sum of all 3 segment times. Results: Colonic transit time was significantly prolonged in HD patients (43.0 +/- 22.2 versus 32.7 +/- 13.7 hours in CAPD patients and 24.3 +/- 11.9 hours in controls; P < 0.001). Increased colonic transit times in the right and rectosigmoid segments, but not the left segment, contributed to the prolongation in total colonic transit time. Age and interdialytic weight gain correlated well with prolongation of total and segmental colonic transit times in HD patients (P < 0.01). Diabetes and female sex in all groups were associated with longer total and segmental colonic transit times, but this trend was not statistically significant. Conclusion: Total, right segmental, and rectosigmoid segmental colonic transit times are prolonged in long-term HD patients compared with CAPD patients and healthy controls. We believe colonic transit time measurement is helpful to tailor therapy because it helps define the pathogenesis of constipation.