Establishing reference intervals for thiamine pyrophosphate and pyridoxal 5’-phosphate in whole blood in a Danish cohort using liquid chromatography tandem-mass spectrometry (LC-ms/ms)

Vitamins B1 and B6 in whole blood (Chromsystems Instruments & Chemicals GmbH, Munich, Germany) for quantitative determination of both TPP and PLP concentration in whole blood, using LC-MS/MS. Reference intervals were determined with non-parametric methods as the 2.5th and 97.5th percentile and presented with 90% confidence intervals (CI). In total 120 blood donors were included. The concentrations of TTP or PLP were not statistically different between sexes just as age did not affect the concentrations, hence, combined reference intervals were employed. The resulting reference intervals are: TPP, nmol/L: 101.0 (90% CI: 96.4-108.5) - 189.0 (90% CI: 184.7-192.0) and PLP, nmol/L: 64.0 (90% CI: 60.9-66.7) - 211.8 (90% CI: 168.3-231.0). In conclusion, reference intervals for whole blood TTP and PLP in a healthy Danish population were established based on a LC-MS/MS method. Furthermore, the reference intervals were not affected by age or sex.