High Prevalence of Hypothyroidism In Systemic Lupus Erythematosus Patients Without an Increase in Circulating Anti-Thyroid Antibodies

Abstract

Because routine investigations are necessary for the early detection of thyroid disease, this study aimed to assess the prevalence of autoimmune thyroid disease (ATD) and thyroid dysfunction (TD) in patients with systemic lupus erythematosus (SLE). Seventy-nine SLE patients (American College of Rheumatology criteria) and 159 control patients with no diagnosis of autoimmune diseases (except for ATD) were consecutively evaluated regarding changes in laboratory assessments of thyroid function and the presence of ATD. ATD was detected in 11.4% of the SLE patients and 13.8% of the control patients (P = .747), whereas TD was detected in 25.3 and 9.4% (P = .002), hypothyroidism was detected in 21.5 and 6.9% (P = .002), and hyperthyroidism was detected in 3.8 and 2.5% (P = .426) of the SLE and control patients, respectively. The mean duration of SLE was longer in patients with TD (P = .036). Mild hypothyroidism was more frequent in the SLE patients with anti-Smith antibodies (P = .029). Because hypothyroidism was more frequent in SLE patients and the frequency of ATD was high in both groups, the authors suggest that TSH and anti-thyroid antibody levels be assessed in SLE patients. ACA = anti-cardiolipin antibodies; ANF = anti-nuclear factor; anti-CCP = anti-cyclic citrullinated peptide; anti-dsDNA = anti-double-stranded DNA; anti-RNP = anti-ribonucleoprotein; anti-Scl70 = anti-topoisomerase I antibodies; anti-SM = anti-Smith antigen antibodies; anti-SS-A/Ro = anti-Sjögren syndrome-related antigen A (Ro); anti-SS-B/La = anti-Sjögren syndrome-related antigen B (La); anti-Tg = anti-thyroglobulin; anti-TPO = anti-thyroid peroxidase; ATD = autoimmune thyroid disease; ENA = extractable nuclear antigen; fT4 = free thyroxine; OR = odds ratio; RF = rheumatoid factor; SLE = systemic lupus erythematosus; SLEDAI = SLE Disease Activity Index; TD = thyroid dysfunction; TSH = thyroid-stimulating hormone; TT3 = total triiodothyronine.