Overview of intestinal adaptation and its stimulation

Total parenteral nutrition (TPN) can be life-saving for many patients with short-bowel syndrome (SBS). However, chronic TPN administration is associated with nutritional deficiencies, septic complications, high health care costs, and life-threatening organ failure. In an effort to rehabilitate SBS patients so they may achieve enteral autonomy, investigators have attempted to stimulate the adaptive response following extensive small-bowel resection. Intestinal adaptation may include: 1) morphological changes of the residual bowel which increase the absorptive surface area; 2) functional changes that increase the absorptive capacity of individual enterocytes and colonocytes; and 3) changes in colonic production and absorption of short-chain fatty acids which improve intestinal vitality and maximize efficiency of energy and fluid absorption. Several peptides, nutrients, cytokines, and other factors promote intestinal adaptation in animals. These "growth" factors may predominantly affect one aspect of the adaptive response while having little or no effect on other physiologic or morphologic parameters. In addition, combined administration of stimulatory agents may be necessary to enhance adaptation. Dietary constituents may have profound positive and negative effects on adaptation and must be considered in developing an overall plan for treatment of the SBS patients. Only a few clinical studies have been performed to evaluate therapeutic regimens for SBS beyond standard supportive care and TPN administration. The combined administration of growth hormone, glutamine and a modified diet to over 225 adults has been shown to eliminate or decrease TPN dependence in 80% of patients receiving this therapy. Further study is required to optimize the treatment of humans with intestinal failure and to determine which patients are most likely to benefit from medical therapy. The authors conclude that the intestinal length to body weight index may be one predictive factor useful for determining which SBS patients will benefit from a trial of pharmacologic manipulation before attempting alternative, potentially more invasive therapies.