Abstract
Children with radiation-induced damage to the hypothalamicpituitary axis have been described in whom the GH response to a pharmacological test is normal but 24 hour GH production is diminished. Therefore we have studied GH secretion under physiological conditions and in response to standard pharmacological stimuli in 14 children (9-17 years), who had received cranial irradiation between two and 14 years earlier. All 14 showed a blunted GH response to an ITT (1-14 mU/l) and, in 12, the GH response to arginine stimulation was also subnormal (1.4-19 mU/l). Physiological GH secretion was studied by measuring integrated GH concentrations in 30 minute blood samples collected over a 24 hour period by a continuous withdrawal pump. Compared to normal controls (n=5), the irradiated patients showed a significant reduction in the mean integrated GH concentration (2.2 : 8.8 mU/l; p < 0.002), median total 24 hour GH output (89.6 : 340.7; p < 0.002) and the median GH output during the first six hours of sleep (32.7 : 210; p < 0.002). There was no significant correlation between the maximum peak GH response to either pharmacological test and the total 24 hour GH output. All 14 children showed a blunted GH response to an ITT as well as a reduced total 24 hour GH output. Therefore we would suggest that in children suspected of radiation-induced GH deficiency pharmacological tests of GH secretion remain useful, the ITT being the test of choice because of the marked radiation sensitivity of the hypoglycaemic stimulus.
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Shalet, S., Ahmed, S. & Beardwell, C. 21 THE EFFECTS OF CRANIAL IRRADIATION ON GROWTH HORMONE SECRETION. Pediatr Res 19, 607 (1985). https://doi.org/10.1203/00006450-198506000-00041
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DOI: https://doi.org/10.1203/00006450-198506000-00041