Thyroid autoantibodies and thyroid dysfunction in rheumatoid arthritis

Lee, Yong Wook; Kim, Dong Sun; Kim, Tae Young; Lee, Chang Beom; Park, Yong Soo; Choi, Woong Hwan; Kim, Tae Wha; Kim, Think You; Jun, Jae Bum; Bae, Sang Cheol; You, Dae Hyun; Kim, Seong Yoon

Abstract

BACKGROUND: Autoimmune thyroid diseases have been shown to occur in association with connective tissue disorders. This study was undertaken to elucidate the prevalence of thyroid autoantibodies and thyroid dysfunction in Korean patients with rheumatoid arthritis (RA).
METHODS
We have compared the prevalence of thyroid autoantibodies in 108 RA patients with 81 age-matched controls. Antimicrosomal antibody (AMA) and antithyroglobulin antibody (ATA) were measured by passive hemagglutinin assay. T3, T4, Free T4, and TSH were measured by chemiluminescence method. Rheumatoid factor was measured by nephelometry. Statistical analysis was performed by chi-square, Fisher's exact test, and Pearson correlation test.
RESULTS
1) The presence of AMA/ATA in patients with RA was significantly higher (28.7%/26.7% in 108 patients) than that of controls (11.1%/9.9% in 81 controls). The positive rates of AMA/ATA in female patients were also higher (28.9%/28.9% in 97 patients) than those of female controls (15.5%/12.1% in 58 controls). 2) Thirty three (17.6%) of 187 patients with RA had the abnormalities of thyroid function; 14 (7.5%) revealed subclinical hypothyroidism, 5 (2.7%) revealed biochemical primary hypothyroidism, 7 (3.7%) revealed sick euthyroid syndrome, and 7 (3.7%) revealed hyperthyroidism.
CONCLUSION
These results suggest that autoimmune thyroiditis is highly associated with RA in Korean patients, showing the increased prevalence of thyroid autoantibodies and thyroid dysfunctions.