Why does ESRD mimic malnutrition?
Studies of experimental uremia and investigations of patients with kidney failure have suggested several mechanisms that may account for the abnormalities misdiagnosed as malnutrition (Figure 1). First, metabolic acidosis is common in kidney failure and acts to stimulate the irreversible destruction of the essential, branched-chain amino acids. In addition, it accelerates the degradation of protein, especially muscle protein (12–14). The increased breakdown of muscle protein is due to activation of the ubiquitin-proteasome proteolytic system, the major system that degrades the bulk of protein in all cells, including muscle cells (15, 16). Recently, we obtained evidence that correcting acidosis in patients treated by chronic ambulatory peritoneal dialysis suppresses the ubiquitin-proteasome system and leads to gain of body weight (17). There also is evidence that acidosis contributes to the low level of serum albumin in dialysis patients (18, 19). Acidosis in kidney failure, therefore,
