Metabolic effects of ghrelin and its potential implications in uremia

Ghrelin is a recently described hormone secreted by the stomach. Ghrelin administration in ad-libitum-fed rodents was shown to increase appetite as well as body weight and body fat content, showing metabolic effects of ghrelin in vivo and suggesting its involvement in the pathogenesis of obesity. However, plasma ghrelin concentration was shown to be inversely correlated with body weight and body fat in people and rodents. Increased plasma ghrelin concentration was also reported during diet-induced weight loss and in malnourished states. These findings suggest that circulating ghrelin is regulated by nutritional state and body fat with a feedback mechanism opposing changes in body composition, with a potential key adaptive role during calorie restriction. Plasma ghrelin concentration was shown to be increased in advanced renal failure and hemodialysis patients. The known metabolic effects of ghrelin and the potential implications of hyperghrelinemia in kidney disease will be discussed in this article. (C) 2005 by the National Kidney Foundation, Inc.