Celiac disease detection in hypothyroid patients requiring elevated thyroid supplementation: A prospective cohort study.

Background: Celiac disease (CD) is associated with hypothyroidism, but the disease prevalence is not thought to be great enough to warrant testing all hypothyroid patients. We hypothesized that hypothyroid patients with concomitant CD would require elevated doses of levothyroxine, and there is a threshold daily dose, above which, hypothyroid patients should be tested for CD.

Methods: Hypothyroid patients presenting to the endoscopy or endocrinology clinics at the University of Vermont Medical Center were included. Patients were categorized by whether or not they required ≥125mcg/day of levothyroxine. A serum tissue transglutaminase (tTG) was performed on enrolled patients. Patients with an elevated serum tTG underwent endoscopy with duodenal biopsies. Symptoms were assessed by the Gastrointestinal Symptom Rating Scale.

Results: Overall, 500 patients were enrolled and 29% (144 patients) required ≥125mcg/day of levothyroxine. CD was detected in 9 patients. The prevalence of CD ranged from 1.8% in our entire cohort to 12.5% in patients requiring ≥200mcg/day of levothyroxine. Eight patients with CD (89%) required ≥125mcg/day of levothyroxine. Patients who required ≥125mcg/day of levothyroxine had a significantly increased risk of CD (p<0.001). CD was detected in 5.6% of patients requiring ≥125mcg/day of levothyroxine.

Conclusions: Hypothyroid patients requiring elevated daily doses of levothyroxine are more likely to have CD. Hypothyroid patients requiring ≥125mcg/day of levothyroxine should undergo serologic testing for CD.