The effect of varying doses of cerebral irradiation on growth hormone production in childhood.

The radiation dose, delivered to the hypothalamic-pituitary region, has been calculated in thirty-nine children irradiated for brain tumours and in seventeen children who had received prophylactic cranial irradiation for acute leukaemia. All subjects had an insulin tolerance test at least 2 years after their radiotherapy. There is a significant inverse correlation between radiation dose and peak GH response. Thirty-seven of the fifty-six patients showed an impaired GH response and thirty-six of these received more than 2900 rads. Only five patients who received such a dose showed normal GH responses and four of these were aged over 13 years when treated. In conclusion, cerebral irradiation is a potent cause of GH deficiency in children.