Number of patients with associated conditions, and the individual 75SeHCAT values in 27 patients with collagenous colitis
| Disease | n | 75 SeHCAT retention (%) |
| Diabetes mellitus | 4 | 9.7; 21; 33; 33 |
| Coeliac disease | 3 | 5.0; 13; 31 |
| Thyroid disease | 2 | 0.8; 15 |
| Rheumatic disease | 2 | 2.0;13 |
| Dermatitis herpetiformis | 1 | 5.0 |
| Pernicious anaemia | 1 | 33 |
| Abdominal surgery | ||
| Cholecystectomy | 1 | 2.0 |
| Billroth I resection | 1 | 31 |
| Cholecystectomy and Billroth I resection | 1 | 0.8 |
| Cholecystectomy and sigmoid resection | 1 | 5.0 |
Eleven patients (41%) had at least one autoimmune disease.