Background: It has been suggested that celiac disease is associated with thyroid disease. Earlier studies, however, have been predominately cross-sectional and have often lacked controls. There is hence a need for further research. In this study, we estimated the risk of thyroid disease in individuals with celiac disease from a general population cohort.
Methods: A total of 14,021 individuals with celiac disease (1964-2003) and a matched reference population of 68,068 individuals were identified through the Swedish national registers. Cox regression estimated the risk of thyroid disease in subjects with celiac disease. Analyses were restricted to individuals with a follow-up of more than 1 yr and with no thyroid disease before study entry or within 1 yr after study entry. Conditional logistic regression estimated the odds ratio for subsequent celiac disease in individuals with thyroid disease.
Results: Celiac disease was positively associated with hypothyroidism [hazard ratio (HR) = 4.4; 95% confidence interval (CI) = 3.4-5.6; P < 0.001], thyroiditis (HR = 3.6; 95% CI =1.9-6.7; P < 0.001) and hyperthyroidism (HR = 2.9; 95% CI = 2.0-4.2; P < 0.001). The highest risk estimates were found in children (hypothyroidism, HR = 6.0 and 95% CI = 3.4-10.6; thyroiditis, HR = 4.7 and 95% CI = 2.1-10.5; hyperthyroidism, HR = 4.8 and 95% CI = 2.5-9.4). In post hoc analyses, where the reference population was restricted to inpatients, the adjusted HR was 3.4 for hypothyroidism (95% CI = 2.7-4.4; P < 0.001), 3.3 for thyroiditis (95% CI = 1.5-7.7; P < 0.001), and 3.1 for hyperthyroidism (95% CI = 2.0-4.8; P < 0.001).
Conclusion: Celiac disease is associated with thyroid disease, and these associations were seen regardless of temporal sequence. This indicates shared etiology and that these individuals are more susceptible to autoimmune disease.