Erythrocyte malondialdehyde release in vitro: a functional measure of vitamin E status.

The definition for a sufficient vitamin E level has often been based on population studies that established the normal range of values for fasting plasma or serum vitamin E and more recently for vitamin E to total lipid ratios. These endpoints for vitamin E replacement strategies may not be readily achievable, particularly in the cholestatic patient for whom it is often impossible to reach and sustain normal levels even with massive doses of vitamin E. Vitamin E is believed to function as an antioxidant in vivo protecting membranes from lipid peroxidation. Malondialdehyde (MDA), a product of polyunsaturated fat peroxidation, was measured as the thiobarbiturate derivative in the supernatant following incubation of erythrocytes in hydrogen peroxide. The two different incubation conditions described here and the subsequent measurement of MDA appear to provide a sensitive functional assessment of vitamin E status. The clinical utility of this assay, which requires just 1.5 to 2.0 ml of whole blood, was demonstrated by comparing the percent of total MDA released from individuals regarded as vitamin E sufficient by conventional methods with vitamin E deficient subjects. The release of MDA from erythrocytes from vitamin E deficient subjects was clearly greater (44.1 +/- 18.8% vs 2.0 +/- 1.8%) than for control subjects (p less than 0.001).