title: Analysis of iodine-131-induced early thyroid hormone variations in Graves' disease.
abstract: OBJECTIVE
  This prospective study aimed to assess iodine-131 (I)-induced early thyroid hormone variations in Graves' disease (GD) and determine the associated factors.
  
  
  METHODS
  One hundred and seventy-one GD patients treated with I were evaluated (47 men, 124 women). I was administered at 9.0±4.9 mCi on average. Serum free triiodothyronine and free thyroxin were measured within 24 h before treatment and 8 (3-14) days after treatment. Patients were divided into increase, no change, and decrease groups, respectively, on the basis of hormone variations after treatment. χ-Test, analysis of variance, and the Kruskal-Wallis test were used to compare groups in terms of sex, age, course of disease, thyroid stimulating hormone receptor antibodies, antithyroid drug (ATD) pretreatment time, time of ATD discontinuation before I treatment, 24 h thyroid I uptake, thyroid weight, I activity, and I activity/thyroid weight (μCi/g). The Spearman method was used for correlation analyses.
  
  
  RESULTS
  Twenty-seven, 20, and 124 cases were assigned to increase, no change, and decrease groups, respectively. Significant differences were found among groups in the time of ATD discontinuation before I treatment [the median duration for methimazole was 11 (5-26), 16 (10-30), and 21 (1-30) days, P=0.000, the median duration for propylthiouracil was 12.5 (5-24), 22 (11-26), and 26 (21-30) days, P=0.000], thyroid weight (93.5±33.6, 90.3±48.8, and 74.1±26.0 g, P=0.003), and μCi/g (84.8±11.8, 100.4±24.9, and 121.1±44.0 μCi/g, P=0.000). Interestingly, μCi/g was negatively and positively correlated to the possibility of hormone increase and decrease, respectively. No significant differences were found in the other parameters assessed.
  
  
  CONCLUSIONS
  At the early stage of I treatment for GD, few patients showed increased thyroid hormone levels. Key factors may include time of ATD discontinuation before I treatment and μCi/g. High μCi/g might decrease thyroid hormone levels in early treatment, making it safe.
authors.affiliation: Department of Nuclear Medicine, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200011, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Xu
authors.forename: Aichun
authors.initials: A
authors.lastname: Gu
authors.forename: Yifan
authors.initials: Y
authors.lastname: Pan
authors.forename: Liwen
authors.initials: L
authors.lastname: Yang
authors.forename: Yubo
authors.initials: Y
authors.lastname: Ma
mesh_terms: D000328:Adult; D000368:Aged; D013956:Antithyroid Agents / Q000627:therapeutic use; D005260:Female; D006111:Graves Disease / Q000097:blood* / Q000532:radiotherapy*; D006801:Humans; D018828:Immunoglobulins, Thyroid-Stimulating / Q000097:blood; D007457:Iodine Radioisotopes / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013963:Thyroid Hormones / Q000097:blood*; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood; D055815:Young Adult
chemical_list: D013956:Antithyroid Agents; D018828:Immunoglobulins, Thyroid-Stimulating; D007457:Iodine Radioisotopes; D013963:Thyroid Hormones; C094372:thyrotropin-binding inhibitory immunoglobulin; D014284:Triiodothyronine; D013974:Thyroxine