Abstract
Cranial irradiation, in a dose of 4500-5500 cGy was given to 9 patients (5 female) at ages ranging from 2-10 years for medullo-blastoma (cranio-spinal irradiation: N=6), astrocytoma (N=1), optic glioma (N=1) and nasopharyngeal rhabdomyosarcoma (N=1). GH secretion was studied 29-126 months post-radiotherapy because of subnormal height velocity. Mean chronological age was 12.5 years and bone age 13.3 years. Mean height was -1.99 SDS compared with -0.60 SDS at the time of treatment. The patients who received spinal irradiation had evidence of diminished spinal growth; mean sitting height -3.60 SDS compared with subischial leg length -1.68 SDS. All subjects had impaired serum GH responses to insulin-induced hypoglycaemia (ITT); mean peak GH 4.5 mU/1 (range 1-10.7 mU/1). The peak GH response to i.v bolus 200 μg GHRH(1-29)NH2 was within the normal young adult range in 5 and marginally subnormal in 2, being in each case greater than during ITT; mean 22.8 mU/1 (range 3.6-61.0 mU/1).
It is concluded that post-irradiation GH deficiency is (i) a common complication in patients treated for cerebral tumours in childhood, (ii) due to a functional disconnection between the hypothalamus and pituitary resulting in defective delivery of GHRH to the somatotrophs, (iii) potentially treatable with long-term synthetic GHRH.
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Savage, M., Grossman, A., Blacklay, A. et al. 56 Cranial irradiation for cerebral tumors in childhood–evidence for a hypothalamic defect in growth hormone release. Pediatr Res 19, 612 (1985). https://doi.org/10.1203/00006450-198506000-00076
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DOI: https://doi.org/10.1203/00006450-198506000-00076