Metoclopramide (MCP), a derivative of procainamide was compared with exercise, arginine, insulin and thyrotropin releasing hormone (TRH) as a prolactin (PRL) releaser in children. The peak response of plasma PRL after oral administration of MCP was greater than that after strenuous exercise and after i.v. administration of pharmacodynamic agents. Normal PRL and TSH responses were observed after TRH administration in all subjects. Variable PRL responses were seen after exercise and after i.v. administration of arginine and insulin, despite significant growth hormone (GH) release following the administration of these agents. MCP produced no increase in plasma TSH. Metoclopramide may be useful for dynamic testing of PRL release in children. It can be taken orally and is free of side-effects.

Basal prolactin concentrations in forty-eight children with acute or chronic renal disease have been compared with those in thirty-four healthy control subjects. Elevated basal prolactin levels and an abnormal prolactin response to intravenous thyrotropin-releasing hormone were found in children with chronic renal failure on maintenance intermittent haemodialysis. No significant change in plasma prolactin concentrations and osmolality was observed before and after haemodialysis, despite a fall in plasma creatinine concentrations. The elevated prolactin levels fell to normal in three patients after successful renal transplantation. It is suggested that the kidney has an important role to play in prolactin metabolism.

Plasma growth hormone (GH) concentrations after insulin and arginine stimulation were estimated in 11 dialyzed and 6 non-dialyzed children with chronic renal failure. Twenty healthy children served as controls. Plasma GH peak concentration and estimation of the total area under the plasma GH concentration-time curve by the trapezoidal rule were used to evaluate results. Elevated basal GH levels and an exaggerated response to the stimuli were seen in several of the patients. The causes of the abnormal GH secretion and the role of high GH levels in carbohydrate intolerance are discussed. No consistent pattern was seen in GH secretion during haemodialysis without glucose in the dialysate. In children undergoing haemodialysis with a fluid containing glucose, plasma GH fell considerably.