title: High failure rates after (131)I therapy in Graves hyperthyroidism patients with large thyroid volumes, high iodine uptake, and high iodine turnover.
abstract: OBJECTIVE
  The objective of this study was to identify patient characteristics positively and independently associated with I-iodide treatment failure in a large cohort of patients with Graves hyperthyroidism treated with either a calculated "standard" activity of 3.7 MBq/mL (0.1 mCi) or 7.4 MBq/mL (0.2 mCi) of thyroid volume.
  
  
  METHODS
  Data on 385 consecutive patients were prospectively collected. Clinical treatment outcome up to 1 year in relation to thyroid volume, 5- and 24-hour I uptake, 5/24-hour I uptake ratio, and the administered activity of radioiodine were analyzed.
  
  
  RESULTS
  Overall treatment results were hypothyroidism in 46%, euthyroidism in 29%, and recurrent hyperthyroidism in 26% of patients. Thyroid volume (P = 0.000), 5/24-hour uptake ratio (P = 0.000), and 5- and 24-hour uptake alone (respectively, P = 0.000 and P = 0.002) were significantly associated with therapy outcome. Patients with a combination of a thyroid volume greater than 50 mL and a 5/24-hour uptake ratio 0.8 or greater showed treatment failure in 70% and 42% (respectively, 3.7 MBq/mL, n = 20; and 7.4 MBq/mL, n = 41).Thyroid volume and 5/24-hour uptake ratio were positively and independently associated with recurrent hyperthyroidism (respectively, odds ratio [OR], 5.3; 95% confidence interval [CI], 2.39-11.76; and OR, 2.97; 95% CI, 1.59-5.59). Higher activities of 7.4 MBq/mL I were associated with a lower risk of treatment failure (OR, 0.34; 95% CI, 0.18-0.62).
  
  
  CONCLUSIONS
  Large thyroid volumes and high 5/24-hour uptake ratios are positively and independently associated with recurrent hyperthyroidism following I therapy in Graves hyperthyroidism. Higher success rates can be achieved when account is taken of these poor prognostic factors. In consequence, these patients should be treated with activities greater than 7.4 MBq/mL.
authors.affiliation: Department of Nuclear Medicine, Institute Verbeeten, PO Box 90120, 5000 LA Tilburg, the Netherlands. jong.d.j@bvi.nl
authors.forename: Jeroen A F
authors.initials: JA
authors.lastname: de Jong
authors.forename: Helena M
authors.initials: HM
authors.lastname: Verkooijen
authors.forename: Gerlof D
authors.initials: GD
authors.lastname: Valk
authors.forename: Pierre M J
authors.initials: PM
authors.lastname: Zelissen
authors.forename: Bart
authors.initials: B
authors.lastname: de Keizer
mesh_terms: D000328:Adult; D005260:Female; D006111:Graves Disease / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D006801:Humans; D006980:Hyperthyroidism / Q000000981:diagnostic imaging* / Q000188:drug therapy*; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics / Q000627:therapeutic use; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009929:Organ Size; D011877:Radionuclide Imaging; D013961:Thyroid Gland / Q000000981:diagnostic imaging* / Q000473:pathology*; D017211:Treatment Failure
chemical_list: D007457:Iodine Radioisotopes