High incidence of thyroid dysfunction despite prophylaxis with potassium iodide during (131)I-meta-iodobenzylguanidine treatment in children with neuroblastoma

Cancer. 2002 Apr 1;94(7):2081-9. doi: 10.1002/cncr.10447.


Background: Treatment modalities like targeted radiotherapy with (131)I-meta-iodobenzylguanidine ((131)I-MIBG) improve survival rates after neuroblastoma (NB). Radiation to the thyroid gland can lead to hypothyroidism and even malignancy. Because hypothyroidism after (131)I-MIBG treatment was reported, the current KI prophylaxis against thyroidal radiation damage was evaluated.

Methods: The incidence, pathogenesis, and consequences of thyroid dysfunction among 42 NB patients treated with (131)I-MIBG were evaluated retrospectively. Efficacy of KI prophylaxis was established by measuring thyroidal radioiodide uptake. Thyroid damage was expressed as thyrotropin elevation (TE, plasma concentration of thyroid stimulating hormone > or = 4.5 mU/L).

Results: The mean followup was 2.3 years (range, 0.1-8.5). The mean number of treatments with (131)I-MIBG was 3.3. Of 428 scintigrams, uptake of (131)I in the thyroid was visible in 92 (21.0%). Twenty two patients (52.4 %) presented TE after a mean period of 1.4 years (range, 0.1-5.8). Clinical signs of hypothyroidism were not observed. Eight patients received suppletion therapy with thyroxine. Thyrotropin elevation was transient in four patients. Of 25 survivors, with a mean followup of 3.5 years, 16 (64%) developed TE. No correlation was found between TE and thyroid visualization after (131)I-MIBG administration or the number of treatments. No abnormalities were seen by ultrasound imaging of the thyroid.

Conclusions: Occurrence of thyroid dysfunction after treatment with (131)I-MIBG for NB is high, in spite of KI prophylaxis. Close followup of thyroid function and structure is required in patients treated with (131)I-MIBG. New ways of protecting the thyroid during exposure to radioiodine should be developed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Iodobenzylguanidine / adverse effects*
  • Adolescent
  • Brain Neoplasms / diagnostic imaging
  • Brain Neoplasms / radiotherapy*
  • Child
  • Child, Preschool
  • Female
  • Follow-Up Studies
  • Humans
  • Incidence
  • Infant
  • Infant, Newborn
  • Male
  • Neoplasm Staging
  • Neuroblastoma / diagnostic imaging
  • Neuroblastoma / radiotherapy*
  • Potassium Iodide / therapeutic use*
  • Premedication
  • Radiation Injuries / diagnostic imaging
  • Radiation Injuries / etiology*
  • Radiation Injuries / prevention & control
  • Radionuclide Imaging
  • Radiopharmaceuticals / adverse effects*
  • Retrospective Studies
  • Thyroid Diseases / diagnostic imaging
  • Thyroid Diseases / etiology*
  • Thyroid Diseases / prevention & control
  • Thyroid Gland / drug effects
  • Thyroid Gland / radiation effects*
  • Thyrotropin / blood
  • Thyroxine / therapeutic use


  • Radiopharmaceuticals
  • Potassium Iodide
  • 3-Iodobenzylguanidine
  • Thyrotropin
  • Thyroxine