Prevalence of thyroid disorders in systemic lupus erythematosus and rheumatoid arthritis

Autoimmune diseases are caused by immune systems reacting against self antigens. One important feature of autoimmune diseases is the tendency for overlap, such that an individual with a specific syndrome is more likely to simultaneously develop a second syndrome. Autoimmune thyroid disorders are frequently associated with autoimmune diseases of other organs such as Rheumatoid Arthritis [RA] and Systemic Lupus Erythematosus [SLE]. The aim of this study was to evaluate the occurrence of thyroid disorders in patients with RA or Systemic Lupus Erythematosus [SLE] In this case-control study, 200 patients with diagnoses of RA or SLE, referred to the rheumatology clinic of Shahid Mohammadi hospital [Bandar abbas- Iran] between May 2004 and December 2006 and following thyroid investigations were categorized in 3 groups [T3, T4, TSH, Anti TPO, and Anti TG] 57 patients with RA, 59 patients with SLE and 66 patients with mechanical low back pain or osteoarthritis as controls. Sub clinical hypothyroidism was more frequent in the RA [10.7%] and SLE [10.2%] groups than in controls [0%] [P < 0.05]. Clinical hypothyroidism was found in 8% of RA patients and 15.2% of SLE patients. None of the controls had clinical hypothyroidism [P < 0.02]. Hyperthyroidism [Graves disease] was found in only 1 patient with RA [1.13%] [P>0.05]. Anti TG and Anti TPO were found more frequently in RA and SLE cases than in controls. Autoimmune thyroid disorders are more frequent in patients with RA and SLE than in controls