Pt with his DM Hypothyroidism now present with passing stools and not gaining weight What is the fuher diagnostic investigation to be done

CELIAC DISEASE The best way to test for celiac disease is with the Tissue Transglutaminase IgA antibody, plus an IgA antibody in order to ensure that the patient generates enough of this antibody to render the celiac disease test accurate. People with celiac disease who eat gluten have higher than normal levels of ceain antibodies in their blood. These antibodies are produced by the immune system because it views gluten (the proteins found in wheat, rye and barley) as a threat. You must be on a gluten-containing diet for antibody (blood) testing to be accurate. ref : harrisons 21st ed