At other times a few tests are conducted. Blood
tests to rule out anemia, stool test to look for white blood
cells, sigmoidoscopy, colonoscopy etc are used to diagnose ulcerative colitis. Braium meal and follow through, endoscopy etc are done to rule out GERD, Crohn’s disease etc. Irritable bowel syndrome is diagnosed by elimination of other causes. Gluten is a complex protein present in four main grains---wheat, rye, barley and oats.