Mechanisms of loss of lean body mass in patients on chronic dialysis.

Abstract

Patients on chronic dialysis treatment often have reduced lean body mass. Certain aspects of bio-incompatibility in dialysis can be viewed as leading to a chronic inflammatory state. In most chronic inflammatory diseases, loss of mean body mass is independent of reduced caloric intake. However, reduced caloric intake accounts for most of the weight loss in these patients and also dialysis patients. Refeeding is associated with increased fat deposition more than restoration of muscle mass. In addition to reduced caloric intake, patients with rheumatoid arthritis, a classic example of a chronic inflammatory disease, have an elevated resting energy expenditure associated with decreased lean body mass. Elevated cellular tumor necrosis factor (TNF) and IL-1 beta production can be demonstrated in these patients. However, in many dialysis patients, increased cytokine production can be 'normal' or reduced. This takes place as the level of malnutrition increases. Thus, cytokines such as IL-1 and TNF play a decreasing role in the pathogenesis of loss of body mass as malnutrition increases and curtails the synthesis of cytokines. Similar to patients with AIDS, progressive disease in patients on chronic dialysis may exhibit subclinical malnutrition which leads to decreased cytokine production. Reduction in cytokine production can be viewed as a protective mechanism.