title: Striving for euthyroidism in radioiodine therapy of Graves' disease: a 12-year prospective, randomized, open-label blinded end point study.
abstract: BACKGROUND
  In China, use of radioiodine therapy is problematic because of the need for lifelong levothyroxine substitution. Our aim was to find an optimum dosing strategy for (131)I treatment of hyperthyroidism due to Graves' disease (GD). We attempted to achieve euthyroidism to avoid long-term levothyroxine treatment.
  
  
  METHODS
  Six hundred patients with GD were randomized into five groups, each comprising 120 individuals, to receive an individual (131)I activity selected from five different ascending activity ranges. The ranges were modulated according to a clinical score system. Follow-up was extended over a 12-year time frame. The primary outcomes were euthyroidism, hyperthyroidism, hypothyroidism, and recurrent hyperthyroidism. The secondary endpoint was the accumulated (131)I activity needed to achieve euthyroidism.
  
  
  RESULTS
  Out of 682 screened patients, 600 entered the study in 1997. Five hundred twenty-nine completed the last follow-up visit at the end of the study in 2009. Group 3 was identified as the study arm that received the optimum radioiodine activity, with 71.8% of the patients maintaining a euthyroid status, 5.8% remaining hyperthyroid, and 22.3% becoming hypothyroid by the end of the study. This group received 1.85-4.07 MBq per gram of thyroid tissue (average administered activity 261 ± 162 MBq). Over the 12-year follow-up period, the recurrence rate was 13.6%. The efficacy of (131)I treatment was related to activities modulated by a clinical score (χ(2) = 82.1, p = 0.000).
  
  
  CONCLUSIONS
  Our protocol effectively treated hyperthyroidism and significantly reduced the hypothyroidism rate. It may be preferable to the intentional induction of permanent hypothyroidism recommended by many experts.
authors.affiliation: Department of Nuclear Medicine, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: Dan Yun
authors.initials: DY
authors.lastname: Chen
authors.forename: Peter F
authors.initials: PF
authors.lastname: Schneider
authors.forename: Xiang Song
authors.initials: XS
authors.lastname: Zhang
authors.forename: Zhi Min
authors.initials: ZM
authors.lastname: He
authors.forename: Jin
authors.initials: J
authors.lastname: Jing
authors.forename: Tang Hua
authors.initials: TH
authors.lastname: Chen
mesh_terms: D000293:Adolescent; D000328:Adult; D013956:Antithyroid Agents / Q000627:therapeutic use; D002648:Child; D005260:Female; D006111:Graves Disease / Q000532:radiotherapy*; D006801:Humans; D006980:Hyperthyroidism / Q000517:prevention & control; D007037:Hypothyroidism / Q000517:prevention & control; D007457:Iodine Radioisotopes / Q000008:administration & dosage / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D055502:Secondary Prevention; D013974:Thyroxine / Q000627:therapeutic use; D016896:Treatment Outcome
chemical_list: D013956:Antithyroid Agents; D007457:Iodine Radioisotopes; D013974:Thyroxine