What is the pathophysiology of growth hormone (GH) secretion?

Updated: Apr 14, 2020
  • Author: Angela Gentili, MD; Chief Editor: George T Griffing, MD  more...
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Answer

GH is released from the anterior pituitary gland in a pulsatile manner. Two hypothalamic hormones control GH secretion: Growth hormone-releasing hormone (GHRH) stimulates GH secretion, and somatostatin inhibits it. The majority of GH secretion occurs at night during slow-wave sleep, when somatostatin release is diminished.

GH stimulates production of IGF-1 in the liver and other tissues. IGF-1 circulates through the bloodstream bound to six specific binding proteins in several combinations. The major serum IGF-binding protein is insulinlike growth factor binding protein-3 (IGFBP-3). Both GH and IGF-1 have important metabolic actions in several tissues.

A single measurement of plasma GH levels is difficult to interpret because of the pulsatile secretion of GH. Levels of IGF-1 vary little during the day; therefore, assays of IGF-1 have been used as a better screening indicator of the status of the GH-IGF-1 axis.


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