Clinical use of glycine intravenous load for diagnosis of growth hormone deficiency.

Intravenous glycine injection (250 mg/kg of body weight) resulted in growth hormone release in normal children but not in those with growth hormone deficiency diagnosed by insulin-induced hypoglycaemia. In the latter significantly higher peak concentrations of serum alpha-amino nitrogen were also found. False negative responses to glycine (no GH release) were observed in two patients of short stature but normal pituitary function. In them the peak levels of serum alpha-amino nitrogen were lower than in those with hypopituitarism. We propose the clinical use of glycine as an inexpensive and innocuous procedure for the detection of GH deficiency in children. A post-glycine GH peak greater than 10-0 mu/l seems to be a good index of an intact GH reserve.