title: The route of administration (oral vs intravenous) does not influence dose or outcome in Graves' disease and unifocal autonomy.
abstract: OBJECTIVE
  In a prospective randomised study, we investigated the influence of the route of administration of radioiodide on dosimetry and therapy outcome.
  
  
  METHODS
  Fifty-four patients suffering from Graves' disease (GD) and 60 patients with unifocal autonomy (UA) participated in the study and were randomly treated with either orally or intravenously administered radioiodide. Pretherapeutic dosimetry was based on single uptake measurements with a calibrated uptake probe system. The radioiodine kinetics during hospitalisation was assessed by daily bedside uptake measurements. Therapeutic dose was determined by half-life and thyroid uptake at the time of discharge using the same uptake probe as for the radioiodine test.
  
  
  RESULTS
  No improvement in accuracy of dosimetry was achieved when radioiodide was administered intravenously. Mean therapeutic doses were identical following intravenous or oral administration. Variation in the achieved dose was slightly higher in the patients receiving oral administration, this being attributable to larger deviations in discrete activities of the capsules administered as compared with the values determined by dosimetry. No differences according to treatment modality were found with regard to therapeutic outcome. Eighty-seven patients attended 6-month follow-up after therapy. In the UA group, successful treatment, defined as a normal or elevated TSH level, was observed in 94% of patients after oral administration and in 80% after intravenous administration; corresponding figures in the GD group were 68% and 65%.
  
  
  CONCLUSIONS
  The causes of individual differences between targeted and therapeutically achieved doses remain undetermined. Variations in the bioavailability of radioiodide or other parameters affecting thyroid status may be involved, and further investigations are needed to clarify this.
authors.affiliation: Clinic for Nuclear Medicine, University of Würzburg, Josef-Schneider Strasse 2, 97080, Würzburg, Germany. schneider_P@nuklearmedizin.uni-wuerzburg.de
authors.forename: Peter
authors.initials: P
authors.lastname: Schneider
authors.forename: Johannes
authors.initials: J
authors.lastname: Biko
authors.forename: Heribert
authors.initials: H
authors.lastname: Hänscheid
authors.forename: Stephan
authors.initials: S
authors.lastname: Hilliger
authors.forename: Christos
authors.initials: C
authors.lastname: Koutsampelas
authors.forename: Michael
authors.initials: M
authors.lastname: Kranzfelder
authors.forename: Stephan
authors.initials: S
authors.lastname: Ladner
authors.forename: Christoph
authors.initials: C
authors.lastname: Reiners
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D002138:Calibration; D005260:Female; D005500:Follow-Up Studies; D006111:Graves Disease / Q000000981:diagnostic imaging* / Q000532:radiotherapy*; D006801:Humans; D007262:Infusions, Intravenous; D007457:Iodine Radioisotopes / Q000008:administration & dosage*; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011874:Radiometry; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000008:administration & dosage; D015203:Reproducibility of Results; D013964:Thyroid Neoplasms / Q000000981:diagnostic imaging; D013972:Thyrotropin / Q000378:metabolism; D013997:Time Factors; D016896:Treatment Outcome
chemical_list: D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D013972:Thyrotropin