Inflammation in ESRD: causes and potential consequences

Malnutrition in end-stage renal disease (ESRD) is characterized by hypoalbuminemia, decreased serum creatinine and prealbumin, and decreased subjective global assessment (SGA) scores. Markers of malnutrition predict mortality and correlate closely with inflammatory markers, including serum cytokines and acute phase proteins. After multiple regression analysis, markers of inflammation become stronger predictors of mortality than nutritional markers, suggesting that malnutrition is a result of inflammation. The etiology of inflammation is variable and includes vascular access infection, bioincompatible dialyzers, back filtration of nonsterile dialysate, periodontal disease, urinary tract infections, and other pyogenic infections. Renal failure also may serve to promote inflammation through protein carbonylation. Differences in care patterns of ESRD patients and genetics may contribute to inflammation as evidenced by lower levels of C-reactive protein (CRP) in Asian populations. Inflammation results in loss of muscle mass and hypoalbuminemia as a consequence of its decreased synthesis and increased catabolism. Vascular disease occurs partly because of changes in lipoprotein structure and function, including oxidation of low-density lipoprotein (LDL) and modification of high-density lipoprotein (HDL) by serum amyloid A (SAA) and loss of apolipoprotein A-I. Leukocyte adhesion is promoted by changes in endothelial structure and function, whereas plasma proteins associated with cardiovascular disease (fibrinogen, lipoprotein[a]; SAA) are increased. Consequences of inflammation in ESRD patients include muscle wasting, erythropoetin resistance, and vascular disease. Whereas improvements in nutrition can increase serum albumin and creatinine levels, identification and removal of the underlying cause of inflammation should be one treatment goal.