Nutrition and mortality in hemodialysis

Abstract

Protein-energy malnutrition is present in a large proportion of maintenance hemodialysis (HD) patients, and it is associated with increased morbidity and mortality. The protein requirements are increased because of the presence of endocrine and metabolic factors related to loss of renal function, the HD procedure, and comorbidity factors, which all stimulate net protein catabolism. The intake protein and energy are frequently reduced because of the underlying disease, psychosocial factors, and uremic anorexia. However, the extent to which underdialysis contributes to anorexia and malnutrition is still not well defined. Malnutrition is generally not recognized as a common direct cause of death as reflected in health statistics, except in the highest age groups. Anthropometric and biochemical signs of malnutrition are associated with increased mortality. A low serum albumin level is a strong predictive risk factor that may reflect not only or mainly protein malnutrition but also the influence of several other morbidity factors (overhydration, infection, chronic disease and others) that may entail an increased risk of death. Low levels of serum creatinine (low muscle mass), serum cholesterol (energy depletion), and BUN and low urea appearance rate (low protein intake) are also correlated to increased mortality. For the prevention and treatment of HD-associated malnutrition, measures should be taken to correct factors that may suppress appetite and increase net protein catabolism (underdialysis, acidosis, low energy intake, comorbid conditions, psychosocial and economic factors). Dietary advice should be given with the aim of ensuring an adequate intake of protein- and energy-giving products. Intradialytic parenteral nutrition may have positive effects on nutritional status when other measures fail. However, the indications for such treatment have not yet been well defined, and the effects on survival, morbidity, and quality of life are not sufficiently well proved. More and better data, generated in prospective, well-controlled studies, are obviously needed before intradialytic parenteral nutrition can be generally recommended as therapy for malnourished HD patients.