Method(s): LC-MS/MS (1).
What is measured: Riboflavin and the flavin cofactor, flavin mononucleotide (FMN).
Performance of the assay
Lower limit of detection (LOD) (riboflavin/FMN): 0.2/0.4 nmol/L.
Within-day CV (riboflavin/FMN): 6/12-18 %; between-day CV: 11-13/13-22 %.
Riboflavin is a marker of vitamin B2 status (2).
Specimen, collection and processing
Patient/subject: Prandial status may have some effect on concentrations of riboflavin, but has no effect on FMN.
Matrix: Riboflavin and FMN are most stable in EDTA plasma.
Volume: Minimum volume is 60 µL, but 200 µL is optimal and allows reanalysis.
Preparation and stability: The plasma fraction must be separated from the blood cells, preferentially within 30 minutes. Samples should be put on ice, and protected from light. Riboflavin is light sensitive. In serum, citrate plasma or heparin plasma, FMN is converted to riboflavin. Measurement of the sum of riboflavin plus FMN is an option in samples that have not been adequately treated.
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Frozen, on dry ice.
Reported values, interpretation
Reported values (riboflavin/FMN): 5-38/5-29 nmol/L.
Intraclass correlation coefficient (ICC) (riboflavin/FMN): 0.79 /0.69.
1. Midttun, O., Hustad, S., and Ueland, P.M. (2009). Quantitative profiling of biomarkers related to B-vitamin status, tryptophan metabolism and inflammation in human plasma by liquid chromatography/tandem mass spectrometry. Rapid Commun Mass Sp 23, 1371-79.
2. Hustad, S., McKinley, M.C., McNulty, H., Schneede, J., Strain, J.J., Scott, J.M., and Ueland, P.M. (2002). Riboflavin, flavin mononucleotide, and flavin adenine dinucleotide in human plasma and erythrocytes at baseline and after low-dose riboflavin supplementation. Clin Chem 48, 1571-77.