Association between inflammatory mediators and muscle mass in long-term hemodialysis patients

Background Muscle wasting is highly prevalent in long-term hemodialysis (HD) patients. Although inflammatory indices have been associated with malnutrition in these patients, the role of inflammation in muscle wasting has not yet been determined. Methods: The relationship between the inflammatory mediators C-reactive protein (CRP) and interleukin-6 (IL-6) and the muscle mass indices thigh muscle area (TMA), measured by computed tomography, and creatinine (Cr) production, estimated by the Cr kinetic model (Cr-CKM), were investigated in 188 HD patients. Results: Serum IL-6 level (7.3 +/- 7.8 pg/mL) was significantly elevated in HD patients, whereas mean serum CRP level (4.8 +/- 7.5 mg/L) remained within the normal range. Similar to serum albumin, muscle mass indices had significantly negative correlations with both serum IL-6 and CRP levels (TMA/dry weight [DW] versus log IL-6, r = -0.28; P < 0.01; TMA/DW versus log CRP, r = -0.38; P < 0.001; Cr-CKM versus log IL-6, r = -0.31; P < 0.01; Cr-CKM versus log CRP, r = -0.24; P < 0.01). Although muscle mass indices also were associated with both age and sex, a multiple regression analysis confirmed that these inflammatory indices were significantly associated with muscle mass in HD patients. Conclusion: Data indicate that muscle wasting is associated closely with inflammatory indices in long-term HD patients. It may be important to clarify the mechanism for the increasing inflammatory status and suppress the inflammatory response in these patients to improve their malnutrition and recover muscle mass.