Background: Inflammatory bowel disease (IBD) is a chronically relapsing disease. It
includes ulcerative colitis (UC) and crohn's disease (CD). Symptoms of IBD could be
conflicting sometimes with irritable bowel syndrome (IBS) of diarrheal type. The ideal
marker for IBD/IBS diagnosis has not yet been identified. B2 microglobulin (B2-M) is a low
molecular weight protein released by activated T and B lymphocytes. It has been shown
to increase in several chronic inflammatory conditions. Objectives: Assessment of the
diagnostic role of (B2-M) in IBS cases presented with diarrhea (IBS-D type) and UC
cases. Methodology: This case control study was conducted at Gastroenterology Unit in
Tropical Medicine Department, Ain- Shams University Hospitals, Cairo, Egypt. Forty
patients with UC, and twenty patients with IBS in addition to twenty healthy persons as
control were included. Results: There was a higher mean of B2-M values among U.C
group (1.93)(mean B2-M in Active UC was 2.26 and 1.61 in inactive disease) compared
to the other two groups(1.51 in IBS and 1.43 in control group) and the difference was
highly statistically significant(P=0.000).Using ROC curve analysis of different cut off
values of (B2-M) for detection of UC cases among IBS cases, we found that at a cut off
value of