The association of Helicobacter pylori infection with Hashimoto's thyroiditis

Autoimmune thyroid diseases (ATD) are multifactorial conditions that result from genetic predisposition in combination with environmental risk factors. Helicobacter pylori infection as an environmental risk factor has been proposed to imitate the antigenic components of the thyroid cell membrane and may play a leading role in the onset of the autoimmune diseases, such as Hashimoto thyroiditis. The aim of this study was to investigate the association between Helicobacter pylori (HP) infection and Hashimoto's thyroiditis (HT). The participants in this case-control study included 43 patients affected by Hashimoto's thyroiditis, and 40 healthy individuals without history of autoimmune disease as the control group. Anti HP IgG and anti-TPO antibodies were determined using ELISA method. Results were considered positive when the IgG anti-HP value was higher than 30 IU/ml and the anti-TPO autoantibody value was higher than 75 IU/ml. The mean TSH level was 18.3±16.8 IU/ml for patients and 2.8±1.2 IU/ml for the control group (P<0.001). 46.5% of the patient group and 10.8% of the control group were infected with HP. The association between HP and Hashimoto's thyroiditis was statistically significant (Odds Ratio=7.2, 95%, Confidence Interval: 2.0- 28.8, P<0.001). The findings show that, there is an association between HP and Hashimoto's thyroiditis. To establish a definite correlation between them, more detailed studies with a more specialized examination and precise consideration regarding species of HP, genetic polymorphism of the host and investigation of environmental factors are needed.