All-trans retinol is a marker of vitamin A status.
Preferred matrix: EDTA plasma.
Volume: Minimum volume is 50 µL, but 200 µL is optimal and allows reanalysis.
Preparation: Serum gel tubes must not be used. Samples should be put on ice, and protected from light.
Reported values: 0.3-8 µmol/L.
Intraclass correlation coefficient (ICC): 0.87.
Serum retinol <0.7 µmol/L has been regarded as indication of deficiency and low liver stores of vitamin A, whereas in vitamin A replete subjects serum retinol is homeostatically regulated and does not reflect liver stores. Retinol binding protein (RBP) correlated with serum retinol but is reduced during inflammation, which may confound the association of retinol concentration with low vitamin A status. Other confounders include reduced kidney function and obesity (2).
1. Midttun, Ø., McCann, A., Aarseth, O., Krokeide, M., Kvalheim, G., Meyer, K., and Ueland, P.M. (2016). Combined measurement of 6 fat-soluble vitamins and 26 water-soluble functional vitamin markers and amino acids in 50 μL of serum or plasma by high-throughput mass spectrometry. Anal Chem 88, 10427-436.
2. Tanumihardjo, S.A., Russell, R.M., Stephensen, C.B., Gannon, B.M., Craft, N.E., Haskell, M.J., Lietz, G., Schulze, K., and Raiten, D.J. (2016). Biomarkers of nutrition for development (BOND)-Vitamin A review. J Nutr 146, 1816S-848S.