Blood lactate levels are better prognostic indicators than TNF and IL-6 levels in patients with septic shock.

Abstract

Both serum levels of tumor necrosis factor-alpha (TNF alpha) and interleukin-6 (IL-6) and blood lactate levels in patients with septic shock have been shown to correlate with prognosis. The aim of the study was to define the relative predictive value of these measures. 38 hospitalized patients with septic shock, including 18 survivors and 20 non-survivors. Blood TNF alpha (immunoradiometric assay), IL-6 (bioassay) and lactate (enzymatic method) levels were serially measured at the onset of septic shock and after 24 and 48 h. TNF alpha levels tended to be higher in the non-survivors than in the survivors at the onset of shock (204 +/- 392 vs 129 +/- 195 pg/ml, p = NS) but decreased similarly in both groups with time (p = 0.03). IL-6 levels at admission were highly variable (9656 +/- 19851 U/ml in the non-survivors and 69,222 +/- 248,804 U/ml in the survivors). Log IL-6 decreased similarly in both groups with time (p = 0.004). Admission blood lactate levels were higher in the non-survivors than in the survivors (6.11 +/- 4.78 mEq/l vs 3.49 +/- 2.00 mEq/l, p < 0.05) and decreased significantly with time in all patients (p = 0.024). However, this decrease was greater in the survivors than in the non-survivors (p = 0.003). These data indicate that the large variability in TNF alpha and IL-6 levels limit their prognostic significance in patients with septic shock. The predictive value of the trend in cytokine levels over time is not superior to that of trends in blood lactate levels.