Celiac disease is a chronic disease affecting digestion and immunity. Gluten consumption triggers the disease, so people with celiac disease can experience damage to their small intestine if they eat any foods that contain gluten, such as wheat products. Celiac disease can cause long-lasting digestive problems and prevent the absorption of essential nutrients. It can cause a huge range of symptoms in different people, including abdominal symptoms like bloating, chronic diarrhea, constipation, or gas, and problems that impact other parts of the body such as fatigue, joint pain, or depression. The causes of celiac disease are unclear although they may involve genetic factors. Diagnosing the disorder can be challenging, and requires a thorough review of an individual's medical history, as well as a biopsy of the intestine. New work may change that, however.
Reporting in The Lancet Gastroenterology, researchers have demonstrated that a blood test to measure the levels of a molecule called tTG-IgA in the blood could be used as a diagnostic for a hallmark of celiac disease called duodenal villous atrophy. In villous atrophy, the intestinal villi show signs of damage like blunting and shortening. Intestinal villi are crucial to nutrient absorption.
In this study, the researchers used samples from 436 patients who were thought to have celiac disease. These were used to diagnose the presence of celiac disease with typical methods like biopsies, and compare these results to those obtained from a tTG-IgA (serum anti-tissue transglutaminase IgA) test.
The study participants were a diverse group of people from around the world. About 68 percent were women and 32 percent were men, and they had an average age of 18. Clinical symptoms were used to separate the volunteers into several groups; one group experienced malabsorption symptoms such as weight loss and anemia; others had only a family history of celiac disease; and some had autoimmune disorders that have been associated with celiac disease.
This study showed that when concentrations of tTG-IgA in the blood were five, ten, or fifteen times higher than what a test considers to be the upper limit of normal (ULN), these levels could indicate celiac disease. Several different tests were used to measure tTG-IgA. The study suggested that if a test indicated ten times the ULN or more, that could be considered a threshold for celiac diagnosis.
About 83 percent of the study participants carried serum tTG-IgA, while 17 percent did not have tTG-IgA at levels high enough to be detected, or none was present. Of the 363 people who had tTG-IgA in their blood, biopsies indicated that 341 had celiac disease while biopsies suggested 22 did not. Seven of the 73 people who did not carry tTG-IgA did have a biopsy that indicated celiac disease. Thus, the tTG-IgA test is not perfect, but it does have significant predictive power. This assay could be particularly useful for children, for whom biopsies are considered too invasive.
Sources: National Institutes of Health, The Lancet Gastroenterology
