Changes in the carbon monoxide diffusing capacity of the lung in ulcerative colitis

The aim of this study was to investigate lung function in patients with ulc erative colitis and to assess the incidence of latent pulmonary involvement in subjects with active and inactive disease. After full colonscopic assessment with multiple mucosal biopsy, the clinica l disease activity of each patient was quantified, using the simple index o f Harvey and Bradshaw. The patients were divided into 2 equal groups: subje cts with active disease (group 1; n=16); and those with inactive disease (g roup 2; n=16). Global spirometry was then performed. A latent pulmonary involvement was found in 17 of 32 patients (53%), the in cidence was higher in the group 1 patients (81%). The majority of patients presented a reduction in the carbon monoxide diffusing capacity of the lung s (DL,CO). The mean DL,CO value was 73.87+/-14.87 in group 1 and 87.31+/-11 .23 in group 2. The DL,CO and KCO reduction correlated significantly with i ntestinal histopathological grading in the group of patients with active di sease (r=0.87, p<0.001; r=0.603, p=0.015). To conclude, a high incidence of pulmonary function abnormalities were iden tified, despite the lack of radiological alterations (High Resolution Compu ted Tomography) and pulmonary symptoms, in ulcerative colitis patients. The se alterations were more common in patients with active disease. The strong correlation between DL,CO values and histopathological grading suggests th at this test may reflect bowel disease activity.