Usefulness of rectally administering [1_13C]-butyrate for breath test in patients with active and quiescent ulcerative colitis

Objective. Impaired butyrate metabolism plays a part in ulcerative colitis (UC). To assess the usefulness of measuring butyrate metabolism as an indication of inflammatory activity, we investigated the rate of butyrate metabolism by breath test after administering [1-C-13] -butyrate rectally to patients with UC. Material and methods. Thirty-eight UC patients (22 active, 16 quiescent) and 15 healthy controls were given [1-C-13] -butyrate enemas. The (CO2)-C-13 production rate was measured by breath test using an infrared spectrometric analyzer. Results. The quantity of expired (CO2)-C-13 was significantly lower in the active than in the quiescent UC and control groups. Cumulative (CO2)-C-13 production at 240 min showed significant negative correlations with the clinical activity index (r= -0.65, p < 0.0001), endoscopic activity index (r= -0.63, P= 0.0001) and histology (r= -0.71, p < d0.0001) in the active UC group. The (CO2)-C-13 production rate was significantly increased in the quiescent stage as compared with the active stage in six UC patients, in whom clinical remission was achieved, in accordance with improvements in the clinical activity index, the endoscopic activity index, histology and fecal butyrate concentrations. Significant inverse correlations between the cumulative (CO2)-C-13 production rate and these three parameters were seen in these six UC patients assessed in both the active and quiescent stages. Conclusions. Measurement of expired (CO2)-C-13, after rectally administering [1-C-13] -butyrate in active and quiescent UC appears to be a promising and reliable method for evaluating disease activity and metabolic changes associated with amelioration of inflammation.