Aims To identify the predictors of CD when presented with LD. Methods 215 LD patients had undergone prospective and systematic evaluation for CD and other recognised associations.The gold-standard diagnosis of CD was based upon the presence of HLA-DQ2 and/or DQ8, persistence or progression of LD following a gluten challenge, symptomatic improvement on a gluten-free diet, and no alternate cause found.Binary logistic regression models, adjusting for age and gender, were subsequently performed to compare presenting variables between CD and non-CD cases, and to determine their sensitivity, specificity, positive and negative predictive values (PPV and NPV).Results CD was diagnosed in 47 cases (22%) and non-CD in 168 cases (78%). There was no statistical difference in demographics, clinical symptoms (i.e. diarrhoea, weight loss, abdominal pain), anaemia or haematinics between the CD and non-CD group.Patients with CD, in comparison to non-CD, were significantly more likely to have a positive family history of CD (21.3% vs. 3.6%, OR 6.81; PPV 62.5%, NPV 81.4%, specificity 96.4%), positive HLA-DQ status (100% vs. 49.4%; PPV 36.2%, NPV 100%, specificity 50.6%), and presence of endomysial antibody [EMA] (49% vs. 0.6%, OR 159; PPV 96%, NPV 87%, specificity 99.4%); all p ≤ 0.001.A normal tissue transglutaminase antibody (TTG) level was seen in 29.8% CD and 82.7% non-CD cases (OR 0.086, p < 0.001; PPV 9.1%). There was no difference in the prevalence of TTG levels 1-2 x upper limit of normal (ULN) between the groups (29.8% CD vs. 14.3% non-CD; PPV 38%). However, TTG levels between 3-20 x ULN were significantly more prevalent in the CD group (31.9% vs. 3%; PPV 66.6% >87.5%),
