Thyroid Autoantibodies in Egyptian Patients with Autoimmune Rheumatic Diseases: Relation to Disease Activity and Functional Impairment

Abstract

Background: Autoantibodies against the thyroid seem to be more common in patients with rheumatic diseases than in the normal population. Their appearance may be linked to an associated autoimmune thyroid disease. Knowing the degree of association between rheumatic and thyroid diseases may help the clinician to make the correct decision. Objectives: The aim of the work was to estimate the prevalence of thyroid autoantibodies among patients with systemic autoimmune rheumatic diseases with or without thyroid disorders and its association with disease activity and functional impairment. Patients and Methods: The current study included 60 patients and 20 healthy controls. Patients were divided into three groups; systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and systemic sclerosis (SSc). Clinical and laboratory assessment were done to all patients including routine laboratory investigations and thyroid function tests (thyroid stimulating hormone [TSH], T3 and T4), and thyroid autoantibodies; anti- thyroglobulin (TgAb) and anti-thyroperoxidase (TPOAb). Results: SLE group had significant (P=0.018) lower age than other groups. Antithyroid antibodies and thyroid disorders were more common in SSc and SLE patients than RA patients and control subjects; however, no significant difference between studied groups. Presence of autoantibodies with and without thyroid disorders was not associated with the activity or functional indexes evaluated. Conclusion: The prevalence of thyroid autoantibodies in SLE and SSc patients was higher than in RA patients. No link could be established between the presence of thyroid autoantibodies and the results from any of the instruments used to measure inflammatory activity and functional impairment in these cases of rheumatic diseases.