title: Radioactive iodine for hyperthyroidism in children and adolescents: referral rate and response to treatment.
abstract: OBJECTIVE
  Radioactive iodine ((131)I) therapy is increasingly viewed as a safe and effective treatment for paediatric and adolescent hyperthyroidism. Our objective was to estimate treatment response and its predictors and describe current referral practices for (131)I therapy.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  One hundred and thirty-one children 30 days-21 years old with laboratory evidence of hyperthyroidism, seen in an academic paediatric and adolescent endocrinology practice.
  
  
  METHODS
  Rate of referral, indications for (131)I, predictors of poor treatment response.
  
  
  RESULTS
  Thirty-eight of 102 patients with persistent hyperthyroidism (37%) received (131)I (160 μCi/g thyroid tissue/(131)I uptake), as did an additional 10 patients initially evaluated by adult thyroidologists. Primary indications were intolerance to (29%) or poor control on (19%) antithyroid drugs, patient preference (50%) and unknown (2%). Of 48 patients treated with (131)I, 89% and 11% became hypothyroid after one and two (131)I doses, respectively. The goal of (131)I therapy was attainment of hypothyroidism. 'Poor treatment response' (seen in 27%) was defined as requirement for a second (131)I dose or failure to achieve hypothyroidism after 6 months. Predictors of poor treatment response included: previous use of antithyroid drugs (37%vs. 0%, P = 0.02), ophthalmopathy (58%vs. 8%, P = 0.002), and an interval of ≥ 12 months from diagnosis to (131)I (50%vs. 10%, P = 0.003). A very elevated free T4 tended to be more prevalent in those with poor response.
  
  
  CONCLUSIONS
  In children and adolescents with hyperthyroidism, high rates of success after (131)I are achievable. Use of antithyroid drugs, pre-existing eye disease and prolonged time to (131)I may confer relative resistance to (131)I.
authors.affiliation: Pediatric Endocrine Unit , MassGeneral Hospital for Children and Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Shana
authors.initials: S
authors.lastname: McCormack
authors.forename: Deborah M
authors.initials: DM
authors.lastname: Mitchell
authors.forename: Melissa
authors.initials: M
authors.lastname: Woo
authors.forename: Lynne L
authors.initials: LL
authors.lastname: Levitsky
authors.forename: Douglas S
authors.initials: DS
authors.lastname: Ross
authors.forename: Madhusmita
authors.initials: M
authors.lastname: Misra
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006980:Hyperthyroidism / Q000532:radiotherapy*; D007223:Infant; D007231:Infant, Newborn; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes