Objective: Growth hormone status was assessed in a cohort of 32 (16 male) adults who had received cranial irradiation (XRT) in childhood as part of their treatment for acute lymphoblastic leukaemia (ALL) and compared with 35 age matched young adults (18 male).
Design: Height and weight were measured in all subjects and the heights of the patients at XRT were obtained from their case notes. Each patient and control underwent two provocative tests of growth hormone (GH) secretion using insulin (0.2 IU/kg body weight) and arginine (20 g/m2). Basal serum insulin like growth factor-1 (IGF-1) and IGFBP-3 (binding protein-3) concentrations were also measured.
Results: The patient group had a significantly lower peak GH response to both provocative tests (P < 0.01), and lower IGF-1 and IGFBP-3 levels compared with the normal controls (P < 0.01). Nine of the patient group were severely GH deficient (peak GH response < 9 mU/l to both provocative agents) and a further 12 patients were GH insufficient (peak GH response < 20 mU/l to both tests with at least one peak GH response > 9 mU/l). Overall a significant median change in height from XRT to final height of -0.5 SDS was found which was even greater in the severely GH deficient group (median change in height of -2.1 SDS).
Conclusion: These data suggest that a significant proportion of adults treated with cranial XRT in childhood with irradiation doses between 18-25 Gy, as part of their treatment for ALL, are severely GH deficient now and should be considered for GH replacement. Changes in GH secretion evolve with time following irradiation-induced damage to the hypothalamic-pituitary axis; therefore long-term surveillance will be required in those remaining patients, in whom GH status is considered currently to be insufficient or even normal.