Objectives: To evaluate the frequency of thyroid disorders in primary Sjögen's syndrome.
Patients and methods: 121 consecutive patients meeting Vitali's criteria for primary Sjögren's syndrome and 74 with rheumatoid arthritis underwent thyroid hormone assays, tests for antimicrosomal and antithyroglobulin antibodies, tests for antinuclear antibodies and antibodies to extractable nuclear antigens. Antimicrosomal and antithyroglobulin antibodies were also assayed in 404 controls.
Results: frequencies were calculated separately in males and females, and data in females were subjected to statistical analysis. As compared with controls, Sjögren's syndrome patients were more likely to have antimicrosomal antibodies (9% versus 17.6%, P < 0.05) and both Sjögren's syndrome and rheumatoid arthritis patients were more likely to have antithyroglobulin antibodies (1% versus 13.4% and 10.9%, respectively, P < 0.0001). Hypothyroidism was more common among Sjögren's syndrome patients (13.4%) than rheumatoid arthritis patients (3.1%) (P < 0.05). Sjögren's syndrome patients with thyroid disorders were less likely to have antinuclear antibodies, rheumatoid factors or a Chisholm's stage 3 or 4 lip biopsy.
Conclusions: our data confirm that thyroid disorders are more common in primary Sjögren's syndrome than in rheumatoid arthritis and controls. Production of autoantibodies and severe histologic lesions were less common in Sjögren's syndrome patients with than without thyroid disorders.