Common serologic test for celiac disease.
Anti-tTG sensitivity is 98% and specificity is 98% for celiac disease duodenal villus atrophy.
False negative results can occur in selective IgA deficiency patients, and patients on a gluten restricted diet, and in patients with seronegative celiac disease.
The positive predictive value of the anti-tTG testing in unselected population is 33% based on the prevalence of celiac disease of 0.7-0.8%.
In high-risk group such as 1st° relatives, the positive predictive value of the test is 72%.
Patients with elevated levels should undergo esophagogastroduodenoscopy while maintaining a gluten diet to determine if celiac disease is present.