title: Development of hypothyroidism during long-term follow-up of patients with toxic nodular goitre after radioiodine therapy.
abstract: OBJECTIVE
  To investigate the cure rate and incidence of hypothyroidism of radioiodine treatment with a calculated dose regimen and an intended thyroid dose of 150 Gy in patients with toxic nodular goitre during long-term follow-up.
  
  
  METHODS
  A total of 265 consecutive patients with toxic nodular goitre were treated between March 2003 and August 2004 at our institute and followed up for a maximum of 8 years. Preliminary radioiodine testing with volumetric measurement of the thyroid by ultrasound as well as individual thyroidal radioiodine uptake and half-life measurements were performed before radioiodine therapy. The estimated radiation dose to the thyroid was 150 Gy.
  
  
  METHODS
  Follow-up controls with respect to success of therapy and development of hypothyroidism were performed 3 months, 1 and up to 8 years after radioiodine treatment. The relation of the achieved thyroid dose to the success rate of treatment and to the incidence of hypothyroidism was analysed.
  
  
  RESULTS
  The cure rates were 85% at 3 months, 98% at 1 year and 98% at the end of follow-up. Above an achieved thyroid dose of more than 120 Gy, there was no significant association between the dose achieved in the thyroid and the cure rate on follow-up. The incidences of hypothyroidism at 3 months, at 1 year and at the end of follow-up were 32%, 55% and 73%, respectively.
  
  
  CONCLUSIONS
  Radioiodine treatment with a calculated dose regimen is a highly effective treatment option in patients with toxic goitre with an overall success rate of 98%. However, radioiodine treatment with an intended thyroid dose of 150 Gy leads to a high incidence of hypothyroidism on long-term follow-up. This finding supports the suggestion that in future intended thyroid doses could be lowered in patients treated with a calculated dose regimen for toxic nodular goitre.
authors.affiliation: Department of Nuclear Medicine, University Hospital of Cologne, Cologne, Germany. deniz.kahraman@uk-koeln.de
authors.forename: Deniz
authors.initials: D
authors.lastname: Kahraman
authors.forename: Christian
authors.initials: C
authors.lastname: Keller
authors.forename: Christina
authors.initials: C
authors.lastname: Schneider
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Eschner
authors.forename: Ferdinand
authors.initials: F
authors.lastname: Sudbrock
authors.forename: Matthias
authors.initials: M
authors.lastname: Schmidt
authors.forename: Harald
authors.initials: H
authors.lastname: Schicha
authors.forename: Markus
authors.initials: M
authors.lastname: Dietlein
authors.forename: Carsten
authors.initials: C
authors.lastname: Kobe
mesh_terms: D000368:Aged; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006044:Goiter, Nodular / Q000532:radiotherapy*; D006801:Humans; D007037:Hypothyroidism / Q000453:epidemiology* / Q000628:therapy; D015994:Incidence; D007457:Iodine Radioisotopes / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D011879:Radiotherapy Dosage; D012189:Retrospective Studies
chemical_list: D007457:Iodine Radioisotopes