A Blood Test to Diagnose IBS

For many of us, getting the diagnosis of irritable bowel syndrome (IBS) is a time-consuming and costly process, involving multiple visits to doctors and many tests. Doctors generally consider all the person’s symptoms, such as diarrhea, constipation, abdominal pain, flatulence, and others, and run a series of tests to rule out other conditions. Wouldn’t it be nice if there were just a simple blood test to diagnose IBS?

A simple blood test

Dr. Mark Pimentel at Cedars-Sinai in Los Angeles has developed one. Based on research that IBS can develop after an episode of acute bacterial gastroenteritis (food poisoning) and data that shows that a significant number of people with IBS have changes in the bacteria in their gut (the most common of which is small intestine bacterial overgrowth (SIBO), Dr. Pimentel developed a blood test that can detect antibodies to a specific protein, vinculin, that is found to be elevated in people with IBS.

In a research study, Dr. Pimentel showed that the blood test was effective in distinguishing between IBS and inflammatory bowel disease (IBD). The clinical study involved 221 patients. Some of them (165) were diagnosed with IBS, 30 had with IBD, and 26 had no gastrointestinal symptoms. The anti-vinculin antibodies were significantly elevated in the people with IBS compared to the other study participants. Dr. Pimentel presented his data at the 78^th Annual Scientific Meeting of the American College of Gastroenterology in 2013.¹

Blood test availability

Diagnostic laboratories around the United States are offering the blood test. Quest Diagnostics calls their test IBSchek, and says it provides a quick and reliable diagnosis of IBS-D, irritable bowel syndrome with diarrhea. IBSchek tests for the presence of vinculin, as well as cytolethal distending toxin B (CdtB), a chemical that is caused by gastroenteritis.²

A positive test result could help people avoid more pricey and unnecessary diagnostic tests, and it could help those patients get treatment with antibiotics that could relieve their IBS symptoms.

Limitations of the blood test

IBS can be caused by food poisoning, but there can be other causes, too. It’s not yet known whether ALL people with IBS have elevated levels of anti-vinculin antibodies. More research is needed to evaluate the specificity of the test for all people with IBS.