Improved radiation protection of the thyroid gland with thyroxine, methimazole, and potassium iodide during diagnostic and therapeutic use of radiolabeled metaiodobenzylguanidine in children with neuroblastoma.
BACKGROUND
During radiolabeled metaiodobenzylguanidine (MIBG) administration in children with neuroblastoma, the thyroid is protected from (123/131)I uptake by potassium iodide. Despite this protection, up to 64% of patients develop thyroid dysfunction. The authors introduce a new method of radiation protection for the thyroid gland.


METHODS
In a prospective cohort study, 34 children with neuroblastoma who received MIBG were given thyroxine, methimazole, and potassium iodide for protection of the thyroid gland. Protection started 1 day before the start of diagnostic 123I-MIBG and was continued until 4 weeks after the last therapeutic 131I-MIBG dose. Follow-up measurements were performed every 3 months after the protection was stopped. Visualization of the thyroid on MIBG images was reviewed by three nuclear medicine physicians. Results were compared with a historic control group of children who had received potassium iodide for thyroid protection during MIBG administration.


RESULTS
After a mean follow-up of 19 months, there were 23 evaluable patients. Thyroid function was normal in 86% of survivors compared with 44% of children in the historic control group (P=0.011; Pearson chi-square test). Scintigraphic visualization of the thyroid diminished substantially after the new protection (21.5% vs. 5.3%, respectively; P=0.000).


CONCLUSIONS
The results of the current study indicate that compared with potassium iodide alone, combined thyroxine, methimazole, and potassium iodide protect the thyroid more effectively against radiation damage from (123/131)I during diagnostic and therapeutic MIBG administration in children with neuroblastoma.
van Santen
Hanneke M
HM
Department of Pediatric Endocrinology, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands. h.m.vansanten@amc.uva.nl
de Kraker
Jan
J
van Eck
Berthe L F
BL
de Vijlder
Jan J M
JJ
Vulsma
Thomas
T
D019797:3-Iodobenzylguanidine / Q000009:adverse effects* / Q000627:therapeutic use; D000970:Antineoplastic Agents / Q000009:adverse effects* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D008713:Methimazole / Q000627:therapeutic use*; D009447:Neuroblastoma / Q000532:radiotherapy*; D011193:Potassium Iodide / Q000627:therapeutic use*; D011837:Radiation-Protective Agents / Q000627:therapeutic use*; D013959:Thyroid Diseases / Q000209:etiology / Q000517:prevention & control*; D013960:Thyroid Function Tests; D013974:Thyroxine / Q000627:therapeutic use*; D016896:Treatment Outcome
D000970:Antineoplastic Agents; D011837:Radiation-Protective Agents; D011193:Potassium Iodide; D019797:3-Iodobenzylguanidine; D008713:Methimazole; D013974:Thyroxine