title: Low iodine diet does not improve the efficacy of radioiodine for the treatment of Graves' disease.
abstract: OBJECTIVE
  Consuming a low-iodine diet (LID) is a widely accepted practice before administering radioiodine (131I) to evaluate and to treat thyroid disease. Although this procedure is well established for the management of patients with differentiated thyroid cancer, its use in patients with benign disease is unclear. So, we aimed to evaluate the influence of a LID on the outcome in patients with Graves' disease (GD) treated with 131I.
  
  
  METHODS
  We evaluated 67 patients with GD who were divided into 2 groups: one group (n = 31) consumed a LID for 1-2 weeks, and the second group (n = 36) was instructed to maintain a regular diet (RD).
  
  
  RESULTS
  The LID group experienced a 23% decrease in urinary iodine after 1 week on the diet and a significant 42% decrease after 2 weeks on the diet. The majority (53%) of the patients in the LID group had urinary iodine levels that were consistent with deficient iodine intake. However, there was no difference in the rate of hyperthyroidism's cure between the LID and the RD groups 6 months after 131I therapy. Furthermore, the therapeutic efficacy did not differ in patients with varying degrees of sufficient iodine intake (corresponding urinary iodine levels: < 10 μg/dL is deficient; 10-29.9 μg/dL is sufficient; and > 30 μg/dL is excessive).
  
  
  CONCLUSIONS
  In the present study, we demonstrated that although a LID decreased urinary iodine levels, those levels corresponding with sufficient or a mild excess in iodine intake did not compromise the therapeutic efficacy of 131I for the treatment of GD.
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Vanessa A
authors.initials: VA
authors.lastname: Santarosa
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Denise M
authors.initials: DM
authors.lastname: Orlandi
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Lia B
authors.initials: LB
authors.lastname: Fiorin
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Teresa S
authors.initials: TS
authors.lastname: Kasamatsu
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Gilberto K
authors.initials: GK
authors.lastname: Furuzawa
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Ilda S
authors.initials: IS
authors.lastname: Kunii
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Rosália P
authors.initials: RP
authors.lastname: Padovani
authors.affiliation: Irmandade Santa Casa de Misericórdia de São Paulo, São Paulo, SP, Brasil.
authors.forename: Marília M S
authors.initials: MM
authors.lastname: Marone
authors.affiliation: Departamento de Diagnóstico por Imagem, EPM, Unifesp, São Paulo, SP, Brasil.
authors.forename: Mário L
authors.initials: ML
authors.lastname: Castiglioni
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: José Gilberto H
authors.initials: JG
authors.lastname: Vieira
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Rui M B
authors.initials: RM
authors.lastname: Maciel
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: Magnus R
authors.initials: MR
authors.lastname: Dias-da-Silva
authors.affiliation: Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brasil.
authors.forename: João R M
authors.initials: JR
authors.lastname: Martins
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003131:Combined Modality Therapy; D005260:Female; D005500:Follow-Up Studies; D005526:Food, Formulated; D006111:Graves Disease / Q000178:diet therapy* / Q000188:drug therapy*; D006801:Humans; D007455:Iodine / Q000008:administration & dosage* / Q000652:urine; D007457:Iodine Radioisotopes / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status; D014131:Trace Elements / Q000494:pharmacology*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D007457:Iodine Radioisotopes; D014131:Trace Elements; D007455:Iodine