PRIMARY HYPOTHYROIDISM AS A CONSEQUENCE OF 131-I-METAIODOBENZYLGUANIDINE TREATMENT FOR CHILDREN WITH NEUROBLASTOMA

Background. 131-I-metaiodobenzylguanidine is a radioiodinated compound selectively concentrated by cells of neuroectodermal origin, includin g neuroblastoma cells, for this reason it may represent a promising tr eatment modality for neuroblastoma in childhood. Although a potential side effect of 131-I-MIBG administration is thyroid dysfunction, relat ively few data are reported about this issue. Methods. A series of 14 long term surviving patients with neuroblastoma who had been treated w ith 131-I-MIBG courses ranging from 2.5 to 5.5 gigabecquerels after su rgical and conventional pharmacologic therapy is reported. Results. Tw elve patients developed primary hypothyroidism that was clinically ove rt in 8 patients and compensated in 4 patients within 6-12 months of c ompletion of 131-I-MIBG administration. Only in two patients was thyro id function spared. Significant correlations between the cumulative do se of 131-I-MIBG and the degree of thyroid failure were not found. Con clusions. Primary hypothyroidism appears to be a common side effect in children with neuroblastoma treated with 131-I-MIBG. This finding sug gests that methods to preserve thyroid function other than oral admini stration of iodide should he sought.