Serum Soluble-Fas, Inflammation, and Anemia in Acute Kidney Injury

Anemia is a common feature in critically ill patients. Serum soluble-Fas (sFas) levels are associated with anemia in chronic kidney disease. It is possible that sFas levels are also associated with anemia in acute kidney injury (AKI) patients. The study aims to investigate the relationship between serum levels of sFas, erythropoietin (Epo), inflammatory cytokines, and hemoglobin (Hb) concentration in critically ill patients with AKI. We studied 72 critically ill patients with AKI (AKI group; n = 53) or without AKI (non-AKI group; n = 19), and 18 healthy volunteers. Serum sFas, Epo, tumor necrosis factor-alpha (TNF-α), interleukin (IL)-6, IL-10, iron status, and Hb concentration were analyzed in all groups. We also investigated the correlation between these variables in the AKI group. Critically ill patients (AKI and non-AKI groups) had higher serum levels of Epo than healthy volunteers. Hb concentration was lower in the AKI group than in the other groups. Serum sFas, IL-6, TNF-α, and ferritin levels were higher in the AKI group. Hb concentration correlated negatively with serum IL-6 (r = -0.37, P = 0.008), sFas (r = -0.35, P = 0.01), and Epo (r = -0.27, P = 0.04), while serum sFas correlated positively with iron levels (r = 0.36, P = 0.008) and IL-6 (r = 0.28, P = 0.04) in the AKI group. In multivariate analysis, after adjusting for markers of inflammation and iron stores, only serum sFas levels (P = 0.03) correlated negatively with Hb concentration in the AKI group. Serum Epo and inflammatory cytokine levels are elevated in critically ill patients with or without AKI. Serum levels of sFas are elevated and independently associated with anemia in critically ill patients with AKI.