Interleukin-6 may mediate malnutrition in chronic hemodialysis patients

Studies were performed to investigate the relationship between serum interleukin-6 (IL-6) and the nutritional status in chronic hemodialysis patients. Serum IL-6 in 45 patients (21 men and 24 women), each with chronic renal failure and having undergone hemodialysis for more than 3 years, was measured before and after a dialysis session. The nutritional status of each patient was evaluated by measuring body mass index (BMI), body weight loss for 3 years, midarm muscle area (MAMA), serum albumin, prealbumin, and insulin-like growth factor-1. Serum IL-6 was significantly higher in the patients undergoing hemodialysis (11.7 +/- 2.8 pg/mL) than in healthy volunteers (< 0.6 pg/mL). There was no further increase in serum IL-6 after a dialysis session when the extracellular water volume was corrected by the ultrafiltrate volume. Predialytic serum IL-6 was significantly correlated with serum albumin (r = -0.4, P = 0.006), cholinesterase (r = -0.51, P = 0.001), body weight change for 3 years (r = -0.48, P = 0.001) and MAMA r = -0.39, P = 0.05). With the patients divided into two groups, a high serum IL-6 (>10 pg/mL) group and low serum IL-6 (<10 pg/mL) group, the body weight loss for 3 years (-4.60% +/- 1.39% v 0.76 +/- 0.75%, P < 0.01) was significantly higher, and the serum albumin level (3.66 +/- 0.10 g/dL v 3.96 +/- 0.05 g/dL, P < 0.05) was significantly lower in those patients with high serum IL-6 than in those with low serum IL-6. The results of a multiple regression analysis indicated that the serum IL-6 level was dependent on the duration of hemodialysis, age, and the dialysis membrane properties. These results suggest that the nutritional status in chronic hemodialysis patients was affected, at least in part, by the circulating IL-6 level. Multiple factors, such as long-term hemodialysis, aging, and the use of a regenerated cellulose membrane dialyzer, were associated with this increased level of IL-6.