Measurement of plasma vitamin K-1 (phylloquinone) and K-2 (menaquinones-4 and-7) using HPLC-tandem mass spectrometry

作者：Riphagen Ineke J^*; van der Molen Jan C; van Faassen Martijn; Navis Gerjan; de Borst Martin H; Muskiet Frits A J; de Jong Wilhelmina H A; Bakker Stephan J L; Kema Ido P

来源：Clinical Chemistry and Laboratory Medicine, 2016, 54(7): 1201-1210.

DOI：10.1515/cclm-2015-0864

• menaquinone
• phylloquinone
• tandem mass spectrometry
• vitamin K

Background: Given the growing interest in the health benefits of vitamin K, there is great need for development of new high-throughput methods for quantitative determination of vitamin K in plasma. We describe a simple and rapid method for measurement of plasma vitamin K 1 (phylloquinone [PK]) and K 2 (menaquinones [MK]-4 and -7). Furthermore, we investigated the association of fasting plasma vitamin K with functional vitamin K insufficiency in renal transplant recipients (RTR).
Methods: We used HPLC-tandem mass spectrometry with atmospheric pressure chemical ionization for measurement of plasma PK, MK-4, and MK-7. Solid-phase extraction was used for sample clean-up. Mass spectrometric detection was performed in multiple reaction monitoring mode. Functional vitamin K insufficiency was defined as plasma desphospho-uncarboxylated matrix Gla protein (dp-ucMGP) > 500 pmol/L.
Results: Lower limits of quantitation were 0.14 nmol/L for PK and MK-4 and 4.40 nmol/L for MK-7. Linearity up to 15 nmol/L was excellent. Mean recoveries were > 92%. Fasting plasma PK concentration was associated with recent PK intake (rho = 0.41, p = 0.002) and with plasma MK-4 (rho = 0.49, p < 0.001). Plasma PK (rho = 0.38, p = 0.003) and MK-4 (rho = 0.46, p < 0.001) were strongly correlated with plasma triglyceride concentrations. Furthermore, we found that MK-4-triglyceride ratio, but not PK-triglyceride ratio, was significantly associated with functional vitamin K insufficiency (OR 0.22 [0.07-0.70], p = 0.01) in RTR.
Conclusions: The developed rapid and easy-to-use LC-MS/MS method for quantitative determination of PK, MK-4, and MK-7 in human plasma may be a good alternative for the labor-intensive and time-consuming LC-MS/MS methods and enables a higher sample throughput.

• 出版日期2016-7