Bile acid diarrhoea (BAD) is a common cause of chronic diarrhoea and can be highly debilitating, causing a significant reduction in the quality of life. It is unfortunately under-recognized and under-diagnosed by clinicians as the cause for this common affliction. This is mostly due to current definitive testing requiring expensive and advanced nuclear medicine technology that is not commonly available or not used at all in some countries (such as the US).
It is important to distinguish BAD from the less common, but more widely recognized cause of chronic diarrhea, ulcerative colitis, because the effective treatment strategies and medications are very different. In the Sensors Special Issue Sensing of Scent, Fragrance, Smell, and Odor Emissions from Biota Sources, Covington et al., demonstrate for the first time the possibility to use a simpler and more cost effective method for distinguishing BAD cases from healthy controls and ulcerative colitis patients based on the detection of volatile organic compounds (VOCs) released from patient urine samples. VOCs and other gases are produced from colonic fermentation and are released through body fluids, thus providing biomarkers in urine, faeces, breath and other biological waste products to assess and monitor gastrointestinal diseases.
In ‘Application of a Novel Tool for Diagnosing Bile Acid Diarrhoea‘, the ‘Fox’, an ‘electronic nose’ instrument that aims to mimic biological olfactory capabilities, was used to detect and recognize odours that emanate from a urine sample. In short, this instrument ‘sniffed’ the enclosed gas space directly above the urine sample, known as the‘headspace’, for VOCs. Also tested was FAIMS (Field Asymmetric Ion Mobility Spectrometry), a fairly recent technology that separates chemical compounds based on their ion mobility in high electric fields, but importantly achieves this separation at room temperature and at atmospheric pressure. Both of these instruments were able to distinguish chemical signatures of BAD from control samples and other ulcerative colitis at a high rate of greater than 80%. Further studies with larger patient groups are planned to confirm these results, understand the best methods for collecting and testing these samples and to choose the most appropriate technology that can be deployed within a medical setting for the identification of this debilitating disease.