Positive thyroid autoantibodies in primary Sjögren syndrome define a subset of patients with milder disease.

OBJECTIVE

To investigate the prevalence, clinical and immune characteristics of patients with primary Sjögren syndrome (pSjS) with positive thyroid autoantibodies (TABs) in Chinese population.

METHODS

391 cases of pSjS were retrospectively analyzed. Patients with positive thyroid autoantibodies (TABs), the presence of either thyroglobulin antibody (TG-Ab), thyroid peroxidase antibody (TPO-Ab), or thyrotropin receptor antibody (TR-Ab), or any combination of these were defined as positive TABs group, and patients without any TABs were defined as negative TABs group. The clinical manifestations and laboratory results were compared between the two groups.

RESULTS

Among the 391 pSjS patients, the TABs were positive in 32.99% (129/391) patients. In the positive TABs group, the prevalence of Raynaud phenomenon was higher, the prevalence of interstitial lung disease (ILD) and low complement 4 (C4) level were significantly lower. Additionally, the levels of serum globulin, immunoglobulin (Ig) G and IgM were higher compared with patients with negative TABs. Age, ILD, RF and anti-SSA were negatively correlated with the coexistence of TABs, while C-reactive protein (CRP) was positively correlated.

CONCLUSION

PSjS was closely related to autoimmune thyroid abnormalities. The prevalence of autoimmune thyroid diseases (AITDs) and TABs in pSjS was high, pSjS patients with positive TABs might represent a milder subset of the disease with a better prognosis with low risk of ILD. Key Points • PSjS was closely related to autoimmune thyroid abnormalities, the prevalence of autoimmune thyroid diseases (AITDs) and TABs in pSjS were high. • The prevalence of interstitial lung disease (ILD) and low complement 4 (C4) level were significantly lower in the positive TABs group. PSjS patients with positive TABs may represent a milder subset of the disease with a better prognosis.