The Prevalence of Thyroid Dysfunction in Patients With Systemic Lupus Erythematosus

BACKGROUND Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disease caused by immune system-mediated tissue damage. Autoimmune thyroiditis (AT) is an organ-specific disease associated with production of a variety of antibodies such as antinuclear antibodies, anti-double-stranded DNA, anti-Ro antibodies and anti-cardiolipin antibodies. OBJECTIVES The aim of this study was to evaluate the prevalence of thyroid dysfunction and thyroid auto-antibodies in patients with SLE and its relation to SLE disease and other autoantibodies. PATIENTS AND METHODS This was a case-control study. The study included a total of 88 patients with SLE and 88 age- and sex-matched healthy volunteers as control group. Two study groups were compared regarding thyroid function test, antinuclear antibody (ANA), antibodies to double-stranded DNA (dsDNA), anti- thyroglobulin antibody (anti-Tg), and anti-thyroid peroxidase (anti-TPO) antibody. RESULTS The mean age of SLE patients and controls were 32.16 ± 9.19 and 32.48 ± 9.47 years, respectively (P = 0.821). Patients had significantly higher prevalence (43.2% vs. 23.9%; P = 0.015) and titers (221.8 ± 570.5 vs. 78.2 ± 277.2; P = 0.036) of antibodies to Tg compared to controls. The patients had significantly lower titers of T3 compared to controls (125.2 ± 35.6 vs. 136.2 ± 26.5; P = 0.021). The titers of T4, TSH and anti-TPO antibody did not differ significantly between the two study groups. CONCLUSIONS Thyroid dysfunction was not higher in SLE patients compared to healthy individuals. However, anti-Tg antibodies were higher in SLE patients. It has not yet been established that thyroid function tests should be performed routinely in SLE patients.