Assessment of vitamin E status in patients with systemic inflammatory response syndrome: Plasma, plasma corrected for lipids or red blood cell measurements?

BackgroundThere is some evidence that the plasma vitamin E status is perturbed as part of systemic inflammatory response and correcting this with other plasma markers may not lead to reliable results. The aim of the present study was to examine the longitudinal inter-relationships between plasma and red blood cell vitamin α-tocopherol in patients with systemic inflammatory response syndrome.Methodsα-tocopherol concentrations were measured, by HPLC, in plasma and red blood cells in normal subjects (n = 67) and in critically ill patients with systemic inflammatory response syndrome (n = 82) on admission and on follow-up.ResultsPlasma α-tocopherol was significantly lower in the critically ill patients compared with the controls (all p < 0.001) with 41% of patients having concentrations below the 95% confidence interval. In contrast, when corrected for cholesterol, α-tocopherol concentrations were significantly higher in the critically ill patients compared with the control group (p < 0.001, 27% above the 95% confidence interval) and when corrected for triglycerides, α-tocopherol concentrations were significantly lower in the critically ill patients compared with the control group (p < 0.001). Red blood cell α-tocopherol corrected for haemoglobin was similar (p = 0.852) in the critically ill patients compared with control subjects. The longitudinal measurements (n = 53) gave similar results.ConclusionsThese results indicate that there is a discrepancy between vitamin E measurements in plasma, in plasma corrected for lipids and in red blood cells. Although the value of correcting vitamin E concentrations by lipids is well established in population studies, the present study indicates that such correction is unreliable in the presence of systemic inflammatory response syndrome and that vitamin E status should be assessed using red blood cell α-tocopherol measurement.