title: Seasonal variation in relapse rate of graves' disease after thionamide drug treatment.
abstract: OBJECTIVE
  Controversy abounds on the issue of seasonal variation in new onset of Graves' disease, partly due to the difficulty of precisely dating the exact start of symptoms. To address the possible relationship between climatic changes and disease activity from a different perspective, we reviewed time of relapse during regular follow-up after successful drug treatment with thionamides.
  
  
  METHODS
  Retrospective analysis of a case series in a university clinic.
  
  
  METHODS
  We consecutively registered patients who experienced re-emergence of hyperthyroidism between 1992 and 2001 after successful antithyroid drug therapy. Excluded were subjects with superimposing painless thyroiditis, in postpartum, on immunomodulatory drugs, or off thionamides prematurely on their own volition.
  
  
  RESULTS
  Fifty-two patients recurred 2 to 36 months after drug cessation. The frequency was higher in spring and summer (March to August) than in autumn and winter (September to February). With a new coated-tube radioreceptor assay, TSH binding inhibitor immunoglobulin activity was detected in sera from 87.5% of the reworsened patients.
  
  
  CONCLUSIONS
  Graves' disease tends to relapse more frequently in spring and summer. Further clinical studies are warranted to clarify underlying mechanism (s) for this seasonal variation.
authors.affiliation: Department of Nuclear Medicine and Diagnostic Imaging, Kyoto University Graduate School of Medicine, Kyoto, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Misaki
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Iida
authors.forename: Kanji
authors.initials: K
authors.lastname: Kasagi
authors.forename: Junji
authors.initials: J
authors.lastname: Konishi
mesh_terms: D000328:Adult; D013956:Antithyroid Agents / Q000627:therapeutic use; D001323:Autoantibodies / Q000097:blood; D005260:Female; D006111:Graves Disease / Q000097:blood / Q000188:drug therapy* / Q000453:epidemiology; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011989:Receptors, Thyrotropin / Q000097:blood; D012008:Recurrence; D012189:Retrospective Studies; D012621:Seasons
chemical_list: D013956:Antithyroid Agents; D001323:Autoantibodies; D018828:Immunoglobulins, Thyroid-Stimulating; D011989:Receptors, Thyrotropin; C094372:thyrotropin-binding inhibitory immunoglobulin