Effect of growth hormone-releasing factor on growth hormone release in children with radiation-induced growth hormone deficiency
Five male children who received cranial irradiation for extrahypothalamic intracranial neoplasms or leukemia and subsequently developed severe growth hormone (GH) deficiency were challenged with synthetic growth hormone-releasing factor (GRF-44), in an attempt to distinguish hypothalamic from pituitary dysfunction as a cause of their GH deficiency, and to assess the readily releasable GH reserve in the pituitary. In response to a pulse of GRF-44 (5 micrograms/kg intravenously), mean peak GH levels rose to values higher than those evoked by the pharmacologic agents L-dopa or arginine (6.4 +/- 1.3 ng/mL v 1.5 +/- 0.4 ng/mL, P less than .05). The peak GH value occurred at a mean of 26.0 minutes after administration of GRF-44. These responses were similar to those obtained in children with severe GH deficiency due to other etiologies (peak GH 6.3 +/- 1.7 ng/mL, mean 28.0 minutes). In addition, there was a trend toward an inverse relationship between peak GH response to GRF-44 and the postirradiation interval. Prolactin and somatomedin-C levels did not change significantly after the administration of a single dose of GRF-44. The results of this study support the hypothesis that cranial irradiation in children can lead to hypothalamic GRF deficiency secondary to radiation injury of hypothalamic GRF-secreting neurons. This study also lends support to the potential therapeutic usefulness of GRF-44 or an analog for GH deficiency secondary to cranial irradiation.
- Research Organization:
- Univ. of California, San Francisco
- OSTI ID:
- 5124011
- Journal Information:
- Pediatrics; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
ENDOCRINE DISEASES
RADIOINDUCTION
SOMATOSTATIN
BIOLOGICAL EFFECTS
STH
METABOLISM
CHILDREN
RADIATION INJURIES
AGE GROUPS
BIOLOGICAL RADIATION EFFECTS
DISEASES
HORMONES
INJURIES
PEPTIDE HORMONES
PITUITARY HORMONES
RADIATION EFFECTS
560151* - Radiation Effects on Animals- Man
551001 - Physiological Systems- Tracer Techniques