Normal Growth Hormone (GH) Response to GHReleasing Hormone in Children with Thalassemia Major Before Puberty: A Possible Age-Related Effect

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Abstract
The plasma GH response to a single iv bolus dose of 2 .mu.g/kg BW synthetic GHRH-(1-44)NH2 was evaluated in 13 prepubertal children with thalassemia major (mean age,7.6 .+-. 0.8 yr) with growth retardation and in 15 prepubertal children with nonendocrine short stature. All of the patients showed a significant increase in plasma GH concentration, with a mean peak of 31.4 .+-. 4.5 .mu.g/L at 15 min (P < 0.001 vs. basal values; range, 18.4-65 .mu.g/L) after GHRH, which was not different from that of the control group of idiopathic short stature children (40.1 .+-. 3.4 .mu.g/L; range,21-65.4 .mu.g/L). All but 1 of the thalassemic patients had a normal GH response to the arginine-insulin stimulation test. The mean plasma insulin-like growth factor-I level was low (0.12 .+-. 0.05 U .times. 103/L; range, <0.02-0.61 U .times. 103/L). Analysis of these results as well as previously reported data indicating that older thalassemic patients have an impaired GH response indicates that there may be an age-related pituitary and/or hypothalamic dysfunction in thalassemic children. This study also confirms that the insulin-like growth factor-I decrease occurs before any alteration in GH secretion. These changes might play a role in the early growth retadation that occurs in these patients.