The association of systemic lupus erythematosus (SLE) and thyroid autoimmunity has been reported by several studies in a wide range of variability. However, from a review of the literature, discrepant results have been reported. The aim of the study was to evaluate the prevalence of clinical and subclinical thyroid disorders in patients with SLE vs sex- and age-matched controls. Thyroid hormones and the presence of antithyroid antibodies were tested and thyroid ultrasonography was performed in 213 patients with SLE vs 426 sex- and age-matched controls, from the same geographic area, with a well-defined status of iodine intake. The odds ratio for subclinical hypothyroidism for female patients with SLE with respect to controls was 4.5 (95% confidence interval [CI], 2.5-8.4); for antithyroid peroxidase antibody (AbTPO) positivity, it was 2.6 (95% CI, 1.7-4.1); and for thyroid autoimmunity, it was 2.9 (95% CI, 2.0-4.4). The mean values of thyroid-stimulating hormone and AbTPO were higher in female SLE patients than in controls (P < .01). A significantly (P < .01) higher prevalence of clinical hypothyroidism and Graves disease was observed in female SLE patients than in controls. No significant difference between SLE patients and controls was detected with regard to free triiodothyronine and thyroxine. In our series, 3% of SLE patients had "nonthyroidal illness syndrome" vs 0 control. Thyroid function and AbTPOs should be tested and ultrasonography should be performed as part of the clinical profile in SLE patients. Subjects at high risk (women, positive AbTPOs, hypoechoic, and small thyroid) should have thyroid function follow-up and appropriate treatment in due course.
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