Prospective screening for coeliac disease in patients with Graves' hyperthyroidism using anti-gliadin and tissue transglutaminase antibodies

Introduction Coeliac disease (CD) is associated with autoimmune thyroid disease (AITD) although its prevalence among those with Graves' hyperthyroidism in the UK is unknown. We determined the prevalence and evaluated the role of screening for CD prospectively in a consecutive cohort of patients with Graves' hyperthyroidism using IgA class antibodies to gliadin (AGA) and tissue transglutaminase (anti-tTG). Methods All patients with Graves' hyperthyroidism attending the thyroid clinic over a 9-month period were offered screening for CD using AGA (normal < 3 mg/l) and anti-tTG (normal < 15 mu/ml). Comparison was made with an age- and sex-matched healthy control group from the local population whose sera were tested for anti-tTG. In patients with borderline or raised anti-tTG (> 7 mu/ml) endomysial antibody (EmA) was measured. Serum IgA was also measured to exclude IgA deficiency. Patients with raised AGA, raised or borderline anti-tTG, positive EmA, IgA deficiency or haematinic deficiencies were offered endoscopic duodenal biopsy. Results A total of 115 patients (97 female and 18 male) with Graves' hyperthyroidism were offered screening tests and 111 accepted. AGA was raised in 15 patients, anti-tTG was raised in two (both positive for EmA) and equivocal in six (one positive for EmA). IgA deficiency was present in three. Four patients were known to have haematinic deficiencies. Twenty-five patients were invited and 19 agreed to have endoscopic duodenal biopsy. Three new patients were found to have CD while two patients were already known to have CD, thus five of 111 patients with Graves' hyperthyroidism had CD. One of 115 healthy controls had a strong positive anti-tTG (> 200 mu/ml) and EmA indicating probable CD. Conclusions Screening 111 consecutive patients with Graves' hyperthyroidism revealed AGA in 14%, anti-tTG in 2% and IgA deficiency in 3%. Two patients were known to have CD. Screening detected three new cases. The prevalence of CD in patients with Graves' hyperthyroidism was 4.5% as compared with 0.9% in matched healthy controls. Routine screening for CD should be considered.