Risk of osteoporosis in microscopic colitis

Patients with microscopic colitis (MC) have several risk factors for osteoporosis. The prevalence of osteopenia and osteoporosis in MC is unknown. The primary purpose of this study was to evaluate bone mineral status in MC.

Patients with MC and disease activity within the last 2 years were included. Bone turnover markers were analyzed and bone mineral density (BMD) was measured with Dual Energy X-ray Absorptiometry (DXA) at inclusion and after one year. Medical history, demographics, risk factors for osteoporosis, disease activity and treatment with cumulative budesonide dosage at least 3 years before inclusion was registered. Adrenal function was tested by adrenocortico-tropic hormone (ACTH) and an ACTH stimulation test at inclusion. Results were compared with age and sex-matched controls.

Fifty MC patients (44 women) were included. Median age 67 (range 45-93); median disease duration 28 month (range 2-163); median cumulative budesonide dosage 702 mg (range 0-5400). No difference in number of patients with osteoporosis or osteopenia and BMD was detected between groups. The bone mineral formation marker specific alkaline phosphatase was lower in MC than controls 12 (5-69) µg/l versus 16 (10-35) µg/l (p < 0.005). Patients more often smoked (34% versus 10%, p = 0.001). Disease duration and cumulative budesonide dose was associated with lower BMD and T-score in hip (Spearman's rho; p < 0.05) with a cut of point of 2500 mg budesonide predicting osteopenia. Budesonide treatment did not affect adrenal gland function.

The risk of osteoporosis in patients with MC is not increased. However, DXA scan is recommended in MC patients with known risk factors or active disease requiring longstanding budesonide treatment. Supplementation of calcium and vitamin-D in patients treated with budesonide is recommended.