Positivity rates of thyroid-associated autoantibodies and thyroid morphological changes in subjects with chronic thyroiditis

Abstract

Abstract Background Most primary hypothyroidism in adults is caused by chronic thyroiditis. Autoantibodies such as anti-thyroglobulin antibody (TgAb) and anti-thyroid peroxidase antibody (TPOAb) are involved in the pathogenesis of chronic thyroiditis. On the other hand, there have been reports of seronegative chronic thyroiditis, which can make the clinical diagnosis difficult clinically. This study aimed to determine the positivity rate of thyroid-related autoantibodies in patients with chronic thyroiditis and to evaluate the differences in clinical findings in seropositive and seronegative chronic thyroiditis. Method In 804 patients with hypothyroidism who attended Kawasaki Medical School Hospital between January 1, 2010 and December 31, 2021, 360 patients were diagnosed with chronic thyroiditis by thyroid antibody testing and ultrasonography. Their thyroid antibody positivity rates and clinical findings were compared. Results Among the patients with chronic thyroiditis, 27.5% were participants with seronegative chronic thyroiditis. The positive rate of each antibody was 68.3% for TgAb and 52.2% for TPOAb. The participants with seropositive chronic thyroiditis had significantly more thyroid gland enlargement on thyroid ultrasound examination (p < 0.05). Thyroid-stimulating hormone was significantly higher in participants with seropositive compared to seronegative chronic thyroiditis. Levothyroxine dosage did not differ between the both groups. Conclusion The present study reveals a positive rate of thyroid-related autoantibodies at the time of diagnosis of chronic thyroiditis. The data of this study also revealed differences in the clinical presentation of seropositive and seronegative chronic thyroiditis.