3.6. Biomarker of sub-clinical vitamin K deficiency

Blood will be collected in an ethylenediaminetetraacetic acid tube, processed after withdrawal and stored at −80 °C as plasma before analysis at Coagulation Profile BV, Maastricht University, the Netherlands. In brief, plasma dp-ucMGP levels will be determined in a single run using the commercially available IVD CE-marked chemiluminescent InaKtif MGP assay on the IDS-iSYS system (IDS, Boldon). Both patient samples and internal calibrators will be incubated with magnetic particles coated with murine monoclonal antibodies against dp-MGP, acridinium-labelled murine monoclonal antibodies against ucMGP, and an assay buffer. The magnetic particles will be captured using a magnet and washed to remove any unbound analyte. Trigger reagents will be added; the resulting light emitted by the acridinium label is directly proportional to the level of dp-ucMGP in the sample^[36]