title: Primary antiphospholipid syndrome and thyroid involvement.
abstract: BACKGROUND
  Data on thyroid involvement in primary antiphospholipid syndrome are scarce and inconclusive.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the frequency of thyroid dysfunction and antibodies in patients with primary antiphospholipid syndrome (PAPS) and the association of these alterations with clinical and immunologic features.
  
  
  METHODS
  The study group included 50 PAPS patients (44 females) with a mean age of 39.7 +/- 11.5 years and mean disease duration of 77.3 +/- 63.5 months. Clinical data related to thyroid dysfunction and PAPS were obtained by chart review, patient interview, and clinical examination. Serum levels of TSH, free T4, antithyroglobulin antibody (TgAb), antithyroperoxidase antibody (TPOAb), thyroid receptor antibody (TRAb), and antiphospholipid autoantibodies were analyzed by standard techniques.
  
  
  RESULTS
  We found no hyperthyroidism among patients and found 22% (11 patients) with hypothyroidism in this sample. There were no differences between the latter patients and the euthyroid group about demographic findings, disease duration, thrombotic or obstetric events, and frequency of antiphospholipid antibodies as well as prevalence of thyroid auto antibodies. The prevalence of thyroid autoantibodies found was 6 patients (12%) with TgAb, 5 with TPOAb (10%), and 2 patients (4%) with both TgAb and TPOAb, comprising 18% of positivity of at least one of the auto antibodies.
  
  
  CONCLUSIONS
  Hypothyroidism is present among 22% of PAPS patients and thyroid autoantibodies in 18% of them. These findings suggest a common pathophysiologic mechanism between antiphospholipid syndrome and autoimmune thyroid diseases.
authors.affiliation: Rheumatology Division, Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo e Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil. jotafc@gmail.com
authors.forename: Jozélio Freire
authors.initials: JF
authors.lastname: de Carvalho
authors.forename: Maria Teresa Correia
authors.initials: MT
authors.lastname: Caleiro
mesh_terms: D000328:Adult; D017152:Antibodies, Antiphospholipid / Q000097:blood; D016736:Antiphospholipid Syndrome / Q000097:blood / Q000150:complications*; D001323:Autoantibodies / Q000097:blood*; D001938:Brazil / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D015995:Prevalence
chemical_list: D017152:Antibodies, Antiphospholipid; D001323:Autoantibodies; C006606:anti-thyroglobulin