Serumalpha- and gama-tocopherol concentrations are commonly used as markers of vitamin E status, but in certain conditions may have a limited diagnostic value. For example, the serum level in patients suffering from ataxia with vitamin E deficiency (AVED syndrome) can fluctuate rapidly during supplementation, rather than achieving a steady state. The erythrocyte tocopherol content is less susceptible to fluctuations after supplementation and is therefore a possible marker of tissue vitamin E status.
The maintenance of serum concentrations of alpha-tocopherol normally depends on the action of alpha-tocopherol transfer protein, secreted by hepatocytes, to preferentially take up alpha-tocopherol from the portal blood, while other forms of vitamin E are more rapidly metabolized and excreted. As a result, blood and cellular concentrations of other vitamin E isomers are lower than those of alpha-tocopherol and have been the subjects of less research.
The erythrocyte tocopherol content is thus a possible marker of tissue vitamin E status in subjects with gross lipid abnormalities and also in subjects suspected of having AVED syndrome, in which there is an abnormality of alpha-tocopherol transfer protein.
Avoid vitamin E containing supplements for 24-48 hours prior to testing
Erythrocyte tocopherol measurement has a role in the investigation of difficult cases of vitamin E deficiency. There is a good correlation between between serum and erythrocyte gamma-tocopherol, but not between serum and erythrocyte alpha-tocopherol, which reflects the important role of alpha-tocopherol transfer protein in the maintenance of body vitamin E status. There are no previous reports in the scientific literature of the erythrocyte /plasma gamma -tocopherol ratio.
Our results for vitamin E-replete subjects suggest a range for the erythrocyte /plasma a-tocopherol ratio of 0.03-0.19 (mean value 0.10), which is lower than that of previous investigators. Our results also suggest a range for the erythrocyte /plasma gamma -tocopherol ratio of 0.11-0.67 (mean value 0.28), which underlines the different physiological mechanisms for the tissue handling of tocopherol isomers.
rbctocopherol.pdf (Click to Download)
Green (lithium heparin) and gold (clotted blood sample) capped blood cllection tubes - must reach Biolab within 24 hours of collection
Postal Samples Acceptable:
1. Miller NJ, Worrell PC, Jasniewicz KP. Erythrocyte tocopherol isomers in the investigation of vitamin E deficiency. Annals of Clinical Biochemistry 2010;47 Supplement 1:116.
2. Chow KC, Distribution of tocopherols in human plasma and red blood cells. Am J Clin Nutr 1975; 28:756-760.
3. Mino M, Kitagawa M, Nakagawa S. Red blood cell tocopherol concentrations in a normal population of Japanese children and premature infants in relation to the assessment of vitamin E status. Am J Clin Nutr 1985;41: 631-638.
4. Lehmann J, Rao DD, Canary JJ, Judd JT. Vitamin E and relationships among tocopherols in human plasma, platelets, lymphocytes, and red blood cells. Am J Clin Nutr 1988; 47:470-474.
5. Thurnam DI, Smith E, Flora PS. Concurrent liquid chromatographic assay of retinol, alpha-tocopherol, beta-carotene, alpha-carotene, lycopene and beta-cryptoxanthin. Clin Chem 1988;34:377-381.
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