Diagnostic value of growth hormone-releasing hormone tests in short children

The values of GH following GHRH stimulation were determined in 32 short children. Firstly, the secretion of GH was measured by two conventional tests (insulin-induced hypoglycemia and arginine tests). According to the response of GH secretion, the children were divided in two groups, the first one with short children suffering from growth hormone deficiency (GHD) (N = 17), and the second with short children without growth hormone deficiency (non-GHD) (N = 15). In the first group (GHD), according to the extent of the GH response to GHRH stimulation, three subgroups were distinguished: in 8 children GH response was < 5 ng/ml, in 5, between 5 and 8 ng/ml, and in 4 the response was > 10 ng/ml. In the second group (non-GHD), the response of GH was between 4.7 and 8.2 ng/ml only in two children, and all other children expressed a response above 10 ng/ml. Comparing the values in both groups by induced hypoglycemia and GHRH test, the response of GH was significantly higher following GHRH stimulation. In the first group the mean value of GH following GHRH stimulation was 10.9 ng/ml (s = 16.35), and in induced hypoglycemic test 1.92 ng/ml (s = 1.86). In the non-GHD group the mean value of GH in the GHRH test was 25.29 ng/ml (s = 14.15), versus GH value in the hypoglycemic test of 11.22 ng/ml (s = 3.045). The authors conclude that the GHRH stimulation test is an acceptable test in differentiation between GH deficiency of pituitary and hypothalamic origin. Still, the GHRH stimulation test alone is not sufficient for the diagnostic procedure of GH deficiency.