AIM: Hashimoto thyroiditis (HT) is the most common cause of goiter and acquired hypothyroidism in children and adolescents living in iodine-sufficient regions. In this study, we aimed to investigate the coexistence of other accompanying autoimmune diseases in patients aged 5–18 years who were diagnosed and followed up at the Pediatric Endocrinology Clinic of our hospital.

MATERIAL AND METHODS: A total of 220 patients aged 5–18 years who were diagnosed with HT at the Pediatric Endocrinology Clinic of the University of Health Sciences Ankara City Hospital. Patient’ age at admission, sex, family history, complaints at admission, comorbidities, physical examination and laboratory findings, and clinical follow-up information were retrospectively reviewed.

RESULTS: Of the 220 patients, 77.7% were female and 22.2% were male, with a mean age of 13.8±3.3 years. Of the 51.4 had euthyroidism, 40.4% had subclinical hypothyroidism,and 8.2% had overt hypothyroidism, respectively. Anti-thyroid peroxidase antibody was detected in 97% of patients and anti-thyroglobulin antibody (anti-Tg) was detected in 74% of patients. There was a family history of autoimmune disease in 36.4% of the patients. Autoimmune disease were present in 45 patients (20.4%). The most common autoimmune diseases in the patients were type 1 diabetes mellitus (T1DM) (14%), celiac disease (5%), skin diseases (2.7%), and rheumatologic diseases (1.3%). No statistically significant differences were found between the sex, age at diagnosis, current age, family history of autoimmune disease and thyroid function status of patients with HT and T1DM.

The mean age of the patients followed up with HT with and without additional autoimmune disease was similar (p=0.644). In both groups, female sex was dominant. However, the number of male patients (35.6%) in the group with additional autoimmune disease was statistically significantly elevated than the group without autoimmune disease (19.9%) (p=0.016). The rate of subclinical hypothyroidism was statistically significantly elevated in the group without additional autoimmune disease (p<0.001). A statistically significant relationship was found between elevated Anti-Tg and additional autoimmune disease (OR=2.32 (95% CI; 1.16–4.56). The prevalence of additional autoimmune disease was increased 2.32 times in patients with elevated anti-Tg levels.

There was no statistically significant correlation between the sex of the patients, their thyroid function status and thyroid autoantibodies (p=0.507). However, the prevalence of celiac disease was statistically significantly elevated in female patients (43.5%) than in male patients (6.7%) (p=0.014). In addition, the prevalence of T1DM was found to be statistically significantly elevated in males (93.8%) compared to females (52.2%) (p=0.007). 13.3% of patients with additional autoimmune disease were under the age of 10 and 64.4% were above the age of 10, this was statistically significant (p<0.01). T1DM was the most common autoimmune disease in both groups.

CONCLUSION: As shown in our study, autoimmune diseases, especially T1DM and celiac disease, are associated with HT. It should be kept in mind that there is an increased risk of autoimmune disease in HT that affects both sexes and increases with age. In particular, regular follow-up of HT patients with elevated anti-Tg levels in terms of autoimmune disease development is important in terms of earlier diagnosis of diseases and reducing their morbidity.