Breath alkanes determination in ulcerative colitis and Crohn's disease

By considering the pathophysiologic basis of inflammatory bowel diseases, a role for excessive lipid peroxidation caused by oxygen free radical compounds has been proposed repeatedly. However, to date only a few studies are available on this topic in human beings. This study was designed to assess breath alkanes in a group of patients with active inflammatory bowel disease by a technique that clearly distinguishes pentane from isoprene, to prevent overestimation of values as in previous studies.

Twenty patients with a diagnosis of active inflammatory bowel disease (10 with Crohn's disease and 10 with ulcerative colitis) were studied. Extension of the disease was similar between patient groups, and all were treated with equivalent doses of steroids and salicylates.

Breath alkanes determination was performed by a standard procedure involving a gas chromatography column able to separate pentane from isoprene.

Overall, significant differences between patients with inflammatory bowel diseases and controls were found for ethane, propane, and pentane, but not for butane and isoprene. Isoprene was clearly distinguished from pentane, demonstrating that the significant elevation of pentane levels in patients with inflammatory bowel diseases is a real phenomenon and not an artifact caused by coelution with isoprene.

An excess of lipid peroxidation is probably an important pathogenetic factor in inflammatory bowel diseases, and this may be assessed through a noninvasive method. Because this method previously also has been shown to be able to evaluate disease activity, it could be a useful tool for studying patients with inflammatory bowel diseases.