Role of soluble receptors for tumor necrosis factor alpha in the development of hypoalbuminemia in hemodialysis patients

Background: Hypoalbuminemia is a significant predictor of mortality in patients on hemodialysis (HD). The cause of hypoalbuminemia in HD patients, however, remains to be clarified. Recent studies have demonstrated that high blood concentrations of soluble receptors for tumor necrosis factor (sTNFRs) are associated with malnutrition in a variety of diseases and that the blood sTNFRs concentrations are elevated in HD patients. Methods: The serum concentrations of tumor necrosis factor alpha, sTNFR (p55 and p80), and interleukin (IL) 6 were measured in 21 HD patients with low (equal to or less than 3.6 g/dl) and in 19 HD patients with normal (equal to or more than 4.0 g/dl) concentrations of serum albumin who were free from acute infection, malignancy, collagen diseases, liver diseases, or surgery. The correlation between these parameters and the degree of hypoalbuminemia was examined. Results: The serum concentrations of sTNFR p80 and IL-6 were significantly higher in patients with hypoalbuminemia as compared with those with normoalbuminemia (sTNFR p80:47.4 +/- 4.7 vs. 35.3 +/- 2.1 ng/ml, p < 0.05; IL-6: 10.8 +/- 2.0 vs. 6.3 +/- 0.5 pg/ml, p < 0.05). In contrast, there was no difference in the serum concentrations of tumor necrosis factor alpha and sTNFR p55 between the two groups. Multivariate regression analysis showed that sTNFR p80 but not IL-6 significantly influenced the serum albumin concentrations. There were no significant differences in body mass index, serum total cholesterol, and normalized protein catabolic rate between the two groups. Conclusions: Our results suggest the development of hypoalbuminemia in some HD patients who do not have any obvious cause of hypoalbuminemia and that high concentrations of sTNFR p80 might contribute to the development of hypoalbuminemia in patients on long-term HD.