14 Jan New diagnostic test for IBS
January 14, 2019
Yes, you read correctly. There is now a blood test for irritable bowel syndrome (IBS)! IBS is a diagnosis based on exclusion because there isn’t a way to test for it. Once other known diseases that cause similar symptoms are ruled out, a patient is diagnosed with IBS. The exclusionary tests include blood tests for celiac disease, stool tests for parasites, lower GI series for blockage, sigmoidoscopy or colonoscopy for colon cancer, CT scan for gallbladder and pancreatic issues, and lactose elimination. As you can imagine, it takes a long time to get all of these tests done. In the meantime, the patient is suffering.
Ibs-smart is a new blood test for IBS from Gemelli Biotech, available in the United States and soon to be expanded to other areas. It can diagnosis IBS-D with up to 98% certainty. IBS-D is one of four sub-types of IBS. IBS with diarrhea predominance is IBS-D. IBS with constipation predominance is IBS-C. IBS with both is IBS-M, and IBS that is difficult to categorize is IBS-U.
The test is highly specific, but only for a small portion of patients with IBS. The specificity is due in large part to work from Dr. Mark Pimentel’s research group. They put the pieces of the puzzle together. One frequent cause of IBS is food poisoning. In about 10% of food poisoning cases, the patient will develop IBS-D or IBS-M within a year. The link between the food poisoning and IBS is two antibodies that the human body makes in response to food poisoning. One is anti-CdtB, which the body produces in response to the cytolethal distending toxin B that is released by bacteria like E. coli and Salmonella. The body also produces anti-vinculin in response to the anti-CdtB. Unfortunately, anti-vinculin is part of an autoimmune response, and it destroys the junctions between the cells in the lining of the intestine. This leads to IBS-D symptoms like diarrhea, nausea, gas, and abdominal pain.
Ibs-smart has its limitations, like any other diagnostic test, but it is a significant step forward in diagnosing and treating IBS. The faster patients can be diagnosed, the sooner they can appropriately manage the symptoms and work towards a treatment plan.
If you’re interested in the scientific details, check out the following scholarly journal article.
Pimentel M, Morales W, Rezaie A, Marsh E, Lembo A, Mirocha J, Leffler DA, Marsh Z, Weitsman S, Chua KS, Barlow GM, Bortey E, Forbes W, Yu A, Chang C. Development and validation of a biomarker for diarrhea-predominant irritable bowel syndromein human subjects. PLoS One. 2015 May 13;10(5):e0126438.