DIAGNOSIS of irritable bowel syndrome (IBS), the most common gastroenterological condition in the USA, can now be achieved with just two blood tests, allowing early diagnosis for millions of sufferers.
Until now, IBS has only been diagnosed following a long and protracted process of ruling out other conditions, frequently including invasive procedures such as colonoscopies and sigmoidoscopies. Dr Mark Pimentel, Director of the Gastrointestinal Motility Program and Laboratory, Cedars-Sinai Medical Center, Los Angeles, California, USA, is the creator of the blood tests. He explained that since there have been no decisive IBS tests, patients have often had to pass from doctor to doctor, repeating tests until they reach a definitive conclusion. “Having an early diagnosis means patients can avoid years of invasive tests and visits to specialists that often leave them with more questions than answers,” explained Dr Mark Pimentel. “With these new blood tests, many patients will now be able to proceed right to therapy for their condition.”
The tests, developed by Dr Pimentel over an 8-year period, identify when IBS has progressed by detecting the existence of antibodies, anti-Cdtb and anti-vinculin, which react to toxins linked with food poisoning. These toxins, made by bacteria including salmonella, damage nerves that are crucial to healthy gut functioning. To confirm the accuracy of the blood tests, Dr Pimentel and his colleagues evaluated almost 3,000 patients aged 18-65, comparing IBS subjects with individuals with inflammatory bowel disease (IBD), coeliac disease, or no gastrointestinal disease at all. They found that the blood tests successfully recognised anti-Cdtb and anti-vinculin antibodies with >90% accuracy, revealing elevated levels in IBS subjects compared to those without IBS.
Consequently, the team announced that these biomarkers can be particularly useful in distinguishing between IBS and IBD in the workup of chronic diarrhoea. The authors recognised that the new tests are limited by a reduced specificity for identifying IBS compared with coeliac disease, although this problem can be easily circumvented by testing for coeliac disease antibodies alongside the IBS tests.
“For the 40 million Americans who have IBS, they now have a test that says ‘you have IBS, it is real, it is an organic disease, it is not a psychological disorder,’ and they can go straight to therapy, or at least get an answer,” said Dr Pimentel.