Celiac disease is an autoimmune disorder that affects roughly one percent of people in the U.S. Those with the disease must avoid foods that contain the gluten protein from wheat, barley or rye. But far more than one percent of the population is following a gluten-free diet, which makes it harder to diagnose real cases of celiac disease.

The two main blood tests used to screen for celiac disease rely on detecting an immune response to gluten, but that immune response gradually disappears in people who avoid gluten.

"Unfortunately, many persons with gluten sensitivity go gluten-free without consulting their clinician for exclusion of celiac disease," said lead study author Dr. Vikas K. Sarna's from Oslo University Hospital in Norway. "In such cases, guidelines recommend . . . performing a gluten challenge involving daily consumption of gluten for up to 8 weeks, followed by an endoscopic procedure for a biopsy taken from the small intestine (duodenum). Our blood test may replace such a gluten challenge and duodenal biopsy."