Is Glucose-6-Phosphate Dehydrogenase Deficiency a Risk Factor for Autoimmune Thyroid Disease? A Retrospective Case–Control Study

Background: The risk of developing thyroid disorders (TDs) in subjects with inherited glucose-6-phosphate dehydrogenase (G6PD) deficiency is unknown. The aim of this study was to explore the association between autoimmune (AITD) and G6PD deficiency in Northern Sardinia, in a population with a high frequency of these two conditions. Methods: In this retrospective single-center case–control study, demographic and clinical data were collected from patients examined in a tertiary referral Gastroenterology Section of a teaching hospital. Results: In 8894 subjects examined (64.7% females), 1218 patients were diagnosed with TDs; more specifically, 767 were diagnosed with AITD and 451 were not (non-AITD). Overall, G6PD deficiency was more prevalent in TD patients compared with patients without TD (controls) (16.7% vs. 11.2%; p < 0.0001). Multivariable logistic regression analysis (after adjusting for age, sex, excess weight and smoking habits), confirmed a higher risk of AITD among G6PD deficient patients with an odds ratio (OR) of 1.36 and 95% confidence interval (CI) of 1.11–1.6, female patients (OR 1.33, 95% CI 1.07–1.65) and overweight patients (OR 1.22, 95% CI 1.03–1.44). Conclusions: The risk of AITD is increased in carriers of G6PD deficiency. A careful assessment of thyroid function is advisable in patients with inherited G6PD defects.