Nutritional aspects in hemodialysis.

The results of cross sectional studies throughout the world indicate that maintenance hemodialysis patients are at risk of malnutrition. Longitudinal studies show that malnutrition is associated with a reduced life expectancy mainly because of cardiovascular and infectious complications. Several factors are responsible for malnutrition of hemodialysis patients. Protein-energy intake is often reduced because of inappropriate dietary restrictions, anorexia, and taste alterations, promoting malnutrition in most patients entering dialysis. Intercurrent illnesses and frequent hospitalizations add to meal disturbances. A state of persistent catabolism may result from acidosis, resistance to anabolic factors such as growth hormone, insulin, and insulin-like growth factor-1, as well as a chronic inflammatory state caused by dialysis membrane and fluid bioincompatibility. In addition, losses of nutrients, including glucose, amino acids, proteins, and vitamins, occur during the dialysis treatment. Careful monitoring of dietary intakes is mandatory even in predialysis patients. In hemodialysis patients, the dose of dialysis should be adapted to correct acidosis and to relieve anorexia caused by accumulation of uremic toxins and hyperleptinemia. When malnutrition is established, active therapeutic interventions should take place, including intradialytic parenteral nutrition if oral supplementation has failed to improve nutritional status. Anabolism has been observed during the administration of recombinant growth hormone and insulin-like growth factor-1. Emerging therapeutic strategies against malnutrition may also involve a short period of daily dialysis.