20 Growth Hormone (GH) Responsiveness to Stimulation by Insulin Hypoglycemia, 2. Arginine, 3. Piromen in normal and Growth Deficient Children

Abstract

Plasma GH levels in 11 normal children, in 5 children with hypothalamic-pituitary disorders, in 8 children with idiopathic GH deficiency and in 4 children with a constitutional growth delay were examined in the fasting state and following stimulation with insulin hypoglycemia, arginine, and bacterial pyrogen (Piromen). Normal children exhibited a marked fluctuation in fasting GH levels (radioimmunoassay). An elevated prestimulatory GH value was associated with a diminished response. Of the 3 stimuli, insulin hypoglycemia resulted in the highest GH levels. In normal children, GH responses to Insulin Hypoglycemia (x 20.4±6.4) Arginine (x 15.2±4.3) and Piromen (x 9.9±2.8) were not significantly different because of the marked variability observed within each group. In children with a constitutional growth delay, both fasting and poststimulatory GH values were indistinguishable from normal. In idiopathic GH deficiency, GH values prior to stimulation (x 2.4±0.4) and after the three stimuli (x 3.6±1.0) were significantly lower than those values observed in the normal or constitutional delay groups. The data suggest 1. Insulin Hypoglycemia, Arginine and Piromen are suitable stimuli with which to evaluate GH responsiveness; 2. failure to respond to stimuli in normal children is associated with elevated resting levels of GH; 3. children with idiopathic GH deficiency have significantly lower pre and post stimulatory GH values than do the normal but do respond better to stimulation than children with pituitary-hypothalamic disorders; 4. constitutional delay in growth is not associated with abnormal GH responsiveness; 5. normal GH secretion can be diagnosed if a resting GH level 6 mμg/ml. (APS)