Clinical and pathological studies in a growth hormone-deficient dwarf.

Postmortem studies were performed in one of three closely related dwarfs. Repeated arginine infusions and insulin tolerance tests never resulted in plasma levels of human growth hormone (HGH) greater than 2.0 ng/ml in any of these three dwarfs. However, pituitary somatotropes in the autopsied subject were well granulated and were reduced in number to 20% of normal. In the absence of a second defect, there should have been substantially higher HGH levels in plasma after provocative stimulation. The clinical and pathological data appear most compatible with (a) deficiency of growth hormone releasing factor, or (b) insensitivity of somatotropes to this material. It seems reasonable to postulate that a major group of dwarfs clinically simulating HGH deficiency can be explained by one of these mechanisms rather than by an absolute deficiency of HGH.