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Objectives: Daily high dose vitamin K supplementation is used empirically by some individuals to improve their “vascular health” or “bone health”. It is unknown if this practice leads to a procoagulant state secondary to increased carboxylation and activity of procoagulant clotting factors. The purpose of this study is to evaluate levels of procoagulant factors II, VII, IX and X and the anticoagulant factors protein C and S, as well as markers of increased thrombin generation (D-dimer, thrombin-antithrombin [TAT] complexes, endogenous thrombin potential) in healthy male adults taking once daily vitamin K 20 mg oral supplementation.
Methods: Eight healthy male adults (age 20-34, 35-49, 50-64, and ≥65) with no prior history of arterial or venous thrombosis will undergo two baseline phlebotomy draws, 14 days apart, to measure levels of Factors II, VII, IX, X, D-Dimer, TAT complexes, Protein C and S activities, D-dimer and thrombin generation potential. Baseline levels will be analyzed to determine physiologic variability of the collected levels and activities. Following the second baseline draw, the participant will start oral vitamin K 20mg daily for 14 days. On day 14, Factors II, VII, IX, X, D-Dimer, TAT complexes, Protein C and S activities, and thrombin generation potential will be re-measured. Baseline and post-vitamin K supplementation data sets will be analyzed to assess any changes.
Results: This study has been approved by the Institutional Review Board of the University of North Carolina Hospitals. Subject recruitment is ongoing. Six subjects have completed the study with no thrombotic events. Blood samples are being batched for simultaneous testing. Anticipated enrollment completion and data evaluation is March 2012.
Conclusion: This pilot study will provide guidance as to whether daily high dose vitamin K supplementation leads to increased procoagulant activity. Results may assist in clinical decision making regarding the safety of vitamin K supplementation.