Peripheral Subresponsiveness to Human Growth Hormone in the African Pygmies

The African pygmies, an ethnic group characterized by proportionate shortness of stature, attain normal plasma concentrations of human growth hormone (HGH) after arginine infusion and insulin-induced hypoglycemia. Their plasma insulin and glucose responses to these stimuli, however, are similar to those of HGH-deficient dwarfs. The administration of exogenous HGH to normal and HGH-deficient persons provokes three characteristic responses: a rise in plasma free fatty acid concentration; an increase in the plasma insulin response to arginine infusion and glucose ingestion; and a fall in the serum urea nitrogen concentration. HGH administration to 19 pygmies failed to induce any of these three responses. Sulfation-factor activity in the pygmies, however, did not differ from that found in normal controls. These observations indicate that the pygmies have endorgan subresponsiveness to the metabolic effects of HGH.