Faecal short-chain fatty acids - a diagnostic biomarker for irritable bowel syndrome?
BACKGROUND
The diagnosis of irritable bowel syndrome (IBS) relies on symptom-based criteria. A valid and reliable biomarker that could confirm the diagnosis is desirable. This study evaluated the properties of faecal short-chain fatty acids (SCFA) as diagnostic biomarkers for IBS.


METHODS
Twenty-five subjects with IBS and 25 controls were included in this explanatory case-control study. Stool samples were analysed for SCFA (acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, and isovaleric acid) with gas chromatography and reported as mmol/l and molar%. In the search for the best way to distinguish between subjects with and without IBS, the total amount and the amount of each of the SCFA were measured, and the proportions and differences between the SCFA were calculated.


RESULTS
In the IBS and control group, the mean age was 46.2 (SD 12.9) and 49.2 (SD 14.6), and the number of females was 13/25 (52 %) and 15/25 (60 %) respectively. The difference between propionic and butyric acid (mmol/l) had the best diagnostic properties, the area under the Receiver Operating Characteristic curve was 0.89 (95 % CI: 0.80-0.98) (p < 0.001). With a cut-off value > 0.015 mmol/l indicating IBS, the sensitivity, specificity, positive and negative likelihood ratio, and diagnostic odds ratio were 92 %, 72 %, 3.29, 0.11 and 29.6 respectively. Similar diagnostic properties were shown for all the IBS subgroups.


CONCLUSIONS
The study indicated that faecal SCFA could be a non-invasive, valid and reliable biomarker for the differentiation of healthy subjects from subjects with IBS.
Department of Research, Innlandet Hospital Trust, N-2381, Brumunddal, Norway. per.farup@ntnu.no.|Unit for Applied Clinical Research, Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science and Technology, N-7491, Trondheim, Norway. per.farup@ntnu.no.
Per G
PG
Farup
Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, P.O. Box 5003, , N-1432, Ås, Norway.
Knut
K
Rudi
Department of Research, Innlandet Hospital Trust, N-2381, Brumunddal, Norway.|Department of Psychology, Faculty of Social Sciences and Technology Management, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.|Department of Public Health, Hedmark University College, N-2418, Elverum, Norway.
Knut
K
Hestad
D015415:Biomarkers / Q000032:analysis; D016022:Case-Control Studies; D005232:Fatty Acids, Volatile / Q000032:analysis*; D005243:Feces / Q000737:chemistry*; D005260:Female; D006801:Humans; D043183:Irritable Bowel Syndrome / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012680:Sensitivity and Specificity
D015415:Biomarkers; D005232:Fatty Acids, Volatile