Plasma growth hormone responses to growth hormone-releasing hormone in children of short stature.

Synthetic GHRH-(1-44)NH2 was administered as an i.v. bolus dose of 2 micrograms/kg to 14 normal short children and 20 children with growth hormone deficiency. In normal short children, mean plasma GH levels reached a peak value of 54.8 mU/L at 30 min; in children with growth hormone deficiency, mean plasma GH levels reached a peak value of 18.6 mU/L at 45 min. In the majority of normal short children, the peak GH values after GHRH administration were greater than GH values after clonidine. The 20 children with growth hormone deficiency had a lower median maximum plasma GH concentration than the 14 normal short children (median 17.1 mU/L vs 49.6 mU/L). There was no significant difference in the distribution of peak GH response time between these two groups. Among 19 children with idiopathic growth hormone deficiency, 47% had a peak GH above 20 mU/L after GHRH. In these children, GHRH administration provided information on the putative hypothalamic etiology of their growth hormone deficiency. These results confirm that GHRH testing is useful for differentiating hypothalamic from pituitary growth hormone deficiency and may be of potential therapeutic value.