Biomarkers may confirm irritable bowel syndrome diagnosis

Written by Matthew Hogg

Wednesday, 16 May 2012 11:36

New research has uncovered differences in the concentrations of proteins called granins between irritable bowel syndrome patients and their healthy peers, suggesting measurement of these proteins could form the basis of lab tests to confirm the diagnosis of the condition.

Irritable bowel syndrome (IBS) is the most commonly diagnosed gastrointestinal (GI) disorder in the developed world, yet this diagnosis is based primarily on a patients symptoms and ruling out other GI diseases with lab testing. As a result it has sometimes been referred to as a "waste basket diagnosis" and has not been taken seriously, when the reality is that the symptoms and suffering of patients are very real.

Now, a pioneering study conducted by scientists from the Sahlgrenska Academy at the University of Gothenburg, Sweden, may have identified specific granins as biomarkers that can be used to develop the first diagnostic lab test for IBS. This would not only make diagnosis an easier process for both doctors and patients, it may also point the way to for the development of new and more effective treatments for IBS.

Granins are common proteins that are secreted by cells of the gut, endocrine and immune systems. They have have previously been shown (in the form of chromogranin A) to serve as biomarkers for other inflammatory diseases in the gut, such as ulcerative colitis and Crohn`s disease.

The researchers hypothesized that IBS patients too would show variations in granin levels compared to healthy individuals. To test the theory they tested stool samples of 82 IBS patients and 29 healthy volunteers to determine concentrations of four common granin proteins.

In a press release lead researcher Lena Ohman said: "Our studies show that IBS patients have higher levels of some granins and lower levels of others in their faeces."

Specifically, the IBS patients in the study were found to have higher levels of chromogranin A (CgA), secretogranin II (SgII) and secretogranin III (SgIII), but lower levels of chromogranin B (CgB). SgII in particular was determined to be a reliable marker for IBS diagnosis, while all three granins that were found to be elevated in the IBS patients showed some correlation to both abdominal pain and colonic transit time.

Ohman and her colleagues condlude that: "Fecal levels of Cg and Sg may be related to the underlying pathophysiology of IBS and of potential importance for symptoms of the patients. Granins also show promise to serve as future biomarkers of IBS. Further studies are needed to explore the potential role of granins in IBS patients."

Source: Öhman L Stridsberg M, Isaksson S, Jerlstad P, Simrén M (2012) Altered Levels of Fecal Chromogranins and Secretogranins in IBS: Relevance for Pathophysiology and Symptoms? The American Journal of Gastroenterology 107:440-47