Antibodies to thyroid peroxidase (TPOAb) and thyroglobulin (TGAb) are hallmarks of autoimmune thyroid disease (AITD). Taitung county locates in the southeast of Taiwan. About one third of the population in Taitung are aboriginals. The iodine uptake is mild deficient in this area. We analyzed the prevalence of thyroid autoantibodies in Taitung.

Serum levels of free thyroxine (fT4) and thyroid stimulating hormone (TSH), and titers of TPOAb and TGAb of patients who visited endocrine clinics at Taitung Christian Hospital (TCH) from August 1, 2020 to July 31, 2021 were collected retrospectively. Patients who had ever received treatment for thyroid disorders were excluded.

Data of 747 patients, 162 male (21.7%) and 585 female (78.3%), were recorded. The patients had a mean age of 48.2 ± 15.7 years. The prevalence of positive TPOAb was 26.1%. Female had higher prevalence of TPOAb than male (28.0% vs 19.1%, p =0.023). Patients of the young age (age <45), middle age (age 45 to <65), and elderly (age ≧65) had prevalence of TPOAb of 31.8%, 23.4%, and 18.4%, respectively (p =0.008). The prevalence of positive TGAb was 19.7%. Female had higher prevalence of TGAb than male (22.4% vs 9.9%, p <0.001). Prevalence of TGAb was not significantly varied between different age groups (22.0%, 19.8%, and 12.8% for young, middle, and elderly, respectively, p =0.120). Prevalence of positive TPOAb in patients with TSH lower, within, or higher than normal reference range was 58.5%, 17.4%, and 39.8 %, respectively (p <0.001). Prevalence of TGAb in patients with TSH lower, within, or higher than normal reference range was 39.6%, 14.1%, and 29.6%, respectively (p <0.001).

As previous studies, we observed higher prevalences of TPOAb and TGAb in female than male. Different with previous reports, our analysis revealed that the prevalence of TPOAb was negatively associated with increasing age. Patients with low or high TSH had higher prevalence of thyroid antibodies than patients with TSH in normal reference range. In literature review, the prevalence of thyroid autoantibodies in Taiwan was seldom discussed. The current observation was conducted at a regional hospital in Taitung. The true impact of population ethnicity and diet habit on presence of AITD in this area remains to be investigated.