Joint Effect of Dietary Protein Intake and Inflammation on Serum Albumin Level in Long-Term Maintenance Hemodialysis (MHD) Patients

Abstract

Serum albumin is one of the strongest mortality-predictors in MHD patients. Yet, the degree to which serum albumin represents dietary protein intake or inflammation is not clear. We hypothesized that inadequate protein intake and inflammation contribute equally to hypoalbuminemia and examined correlates of low serum albumin <3.8 g/dL in 812 MHD patients in whom interleukin-6 (IL-6) and normalized protein nitrogen appearance (nPNA), also known as normalized protein catabolic rate (nPCR), were also measured. Logistic regression estimated odds ratios were employed and spline models were plotted to examine the likelihood of low serum albumin <3.8 g/dL. Mean age (±SD) of patients was 54±15 years; 53% of patients were men, 50% Hispanic, 31% African-American and 55% diabetic. The unadjusted correlation coefficients of IL-6 and nPNA with serum albumin were -0.36 and +0.20, respectively (p<0.001 for each comparison). The likelihood for an albumin <3.8 gr/dL increased linearly with decreasing nPNA and rising serum IL-6. This trend was steeper with increasing serum IL-6 up to a concentration of 30 ng/ml (Figure). Hence, both low protein intakes and a high state of inflammation are associated with low serum albumin in MHD patients.fx1