Gastrointestinal effects of growth hormone.

GH receptor immunoreactivity is found throughout the gastrointestinal tract. GH has proliferative effects upon intestinal epithelium, and influences enteroendocrine cell secretion, calcium absorption, and intestinal amino acid and ion transport. The proliferative effects of GH may be reflected in the increased incidence of neoplastic colonic polyps in individuals with long-term GH excess reported by some investigators. GH also increases hepatic cytochrome P450 expression, potentially altering drug and steroid hormone metabolism. Current clinical research efforts include the use of exogenous GH as a stimulant of gut growth and adaptation in patients who have undergone massive intestinal resection. Exogenous GH is also being studied in animal models of critical illness where it appears to increase intestinal glutamine uptake, which may prevent deterioration of the intestinal mucosal barrier.