The effects of arginine, insulin and metoclopramide on growth hormone, prolactin and cortisol release in children.

The growth hormone (GH) and prolactin (PRL) responses to metoclopramide (MCP) were compared to those with arginine and insulin-induced hypoglycaemia in eight children. While a significant rise in GH release after stimulation with arginine and insulin occurred in all subjects (P less than 0.05), no significant increase after MCP ingestion was observed. Metoclopramide, a dopamine antagonist, stimulated PRL release in all children, while arginine and insulin-induced hypoglycaemia stimulation tests showed variable PRL responses. A statistically significant increase in cortisol secretion 5 h following MCP was observed (trend test, Cox & Stuart, 1955) (P less than 0.05), but the plasma concentration at this time was still within the normal range. Metoclopramide stimulation is not a suitable test for growth hormone deficiency in children.