title: The occurrence of hypothyroidism following radioactive iodine treatment of toxic nodular goiter is related to the TSH level.
abstract: BACKGROUND
  Strategies to increase frequency of euthyroidism following radioactive (RAI) treatment of hyperthyroidism are required.
  
  
  OBJECTIVE
  To examine the role of TSH in development of hypothyroidism post RAI treatment in patients with Graves' disease (N = 98) or toxic nodular goiter, TNG (N = 88).
  
  
  METHODS
  This retrospective study examined thyroid status over a mean of 3.7 years post-RAI.
  
  
  RESULTS
  Although RAI dose was significantly higher in TNG group, hypothyroidism occurred more frequently in Graves' disease (71.4 and 22.7%) P < 0.001. The TSH levels at the time of RAI treatment were lower in TNG patients who remained euthyroid, (0.4+/-0.1 vs. 1.2+/-0.5 mU/l, P < 0.0022).
  
  
  CONCLUSIONS
  A higher frequency of euthyroidism occurs in patients with TNG than with Graves' disease following RAI, particularly when suppressed TSH levels were suppressed at time of RAI-treatment.
authors.affiliation: Department of Endocrinology and Diabetes Mellitus, St. Vincent's University Hospital, Elm Park, Dublin 4, Ireland. adamalih@gmail.com
authors.forename: H I
authors.initials: HI
authors.lastname: Adamali
authors.forename: J
authors.initials: J
authors.lastname: Gibney
authors.forename: D
authors.initials: D
authors.lastname: O'Shea
authors.forename: M
authors.initials: M
authors.lastname: Casey
authors.forename: T J
authors.initials: TJ
authors.lastname: McKenna
mesh_terms: D000328:Adult; D005260:Female; D006044:Goiter, Nodular / Q000097:blood / Q000532:radiotherapy*; D006111:Graves Disease / Q000097:blood / Q000532:radiotherapy*; D006801:Humans; D007037:Hypothyroidism / Q000097:blood* / Q000209:etiology; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013972:Thyrotropin / Q000097:blood*
chemical_list: D007457:Iodine Radioisotopes; D013972:Thyrotropin