Neuroendocrine changes induced by craniospinal radiation in children with acute lymphoblastic leukemia and medulloblastoma

In order to investigate effects produced by external cranial irradiation on neuroendocrine systems. GH secretion (elicited by oral clonidine and by GRF-29 as iv bolus) and TSH and PRL responses to an iv bolus of TRH were evaluated in children previously irradiated for LLA (n-7) or medulloblastoma (n-3). Growth velocity was also periodically evaluated. Three years after radiotherapy, while a normal GH response to clonidine challenge was observed in 60% of cases, growth velocity was impaired in 83.3% of them. GH release induced by GRF-29 was normal in another 60% of patients. Either basal TSH values or its' response to TRH were significantly increased in the three medulloblastomas, in spite of clinical and biochemical euthyroid status of these patients. Our data indicate that cranial radiotherapy produces functional neuroendocrine alterations; specificity and degree of these are dependent on the dose received. Therefore, to allow a suitable replacement hormonal therapy as soon as possible, this type of patients need a periodic evaluation of their endocrine status.