A critical review of the clinical relevance of growth hormone and its measurement in the nuclear medicine laboratory

A wide variety of metabolic and stressful stimuli, both physical and psychologic, produce rapid elevation of plasma growth hormone (GH). In addition, spontaneous elevation of GH occurs during the day, and a rise in GH occurs in association with the initial slow-wave sleep episode at night. Although the identity of the long-sought GH releasing factor has not yet been established, a hypothalamic factor inhibiting GH release named somatostatin has been identified and synthesized. Most, if not all, of the GH rises are mediated by neural mechanisms, and therefore they may be disrupted by many disease processes affecting the pituitary or the hypothalamus...