Thyroid dysfunction in patients with systemic lupus erythematosus (SLE): relation to disease activity.

We examined the prevalence of thyroid dysfunction and the production of anti-thyroid antibodies (ATA) in patients with systemic lupus erythematosus (SLE) and assessed the association between ATA production and SLE disease activity status. Seventy-seven patients who met the American College of Rheumatology classification criteria for SLE participated in the study. Fifty-two individuals served as a control group. Demographic, clinical information and SLE disease activity (SLEDAI) status were collected from all patients. The sera of all participants were tested for free thyroxine (FT4), thyroid-stimulating hormone (TSH), anti-thyroglobulin (ATg) and anti-thyroid peroxidase (TPO). A SLEDAI score of > or =6 was considered clinically significant. The results of the thyroid function tests and ATA were compared between the study group and the control group. ATA levels were compared between the patients with a SLEDAI score of > or =6 to those with a SLEDAI score of <6. Hypothyroidism was detected in 11.6% of SLE patients compared to 1.9% in the control group. None of the patients or controls had evidence of hyperthyroidism. No statistically significant difference was observed in the levels of ATg or TPO between the study group and the control group. No correlation was found between ATA levels and the degree of the disease activity. Among the different variables tested in this study, hypothyroidism was the only significant abnormal finding in SLE patients. No association was found between the SLEDAI score and the prevalence of ATA production. Larger controlled, longitudinal studies are necessary to confirm these findings and elucidate the role played by ATA in the pathogenesis of thyroid dysfunction in SLE patients.