title: Temporal variations in plasma vitamin K and lipid concentrations and clotting factor activity in humans.
abstract: There is no information available on temporal variability in plasma vitamin K concentrations and its relationship to coagulation processes. We investigated the possible existence of temporal changes in plasma vitamin K and lipid concentrations and activity of clotting factors II, VII, IX, and X and relationships between these variables. Plasma vitamin K and lipid concentrations and clotting factor activity were measured at four-hour intervals for 28 hours in a group of healthy volunteers. Temporal variations existed in plasma vitamin K concentrations, with a mean maximum at 22:00 hr and a mean minimum (32% of the maximum) at 10:00 hr. Plasma triglycerol concentrations mirrored the changes in vitamin K concentrations. Mean factor VII activity was positively correlated with mean total plasma cholesterol concentrations (r = 0.714; P < 0.0001) and with mean plasma low density lipoprotein (LDL) cholesterol concentrations (r = 0.461; P < 0.0001). No distinct correlations were found between plasma vitamin K concentrations and either high density lipoprotein (HDL) or LDL cholesterol concentrations, or between triglycerol, HDL, or LDL cholesterol concentrations and functional activity of factors II, IX, and X. Plasma vitamin K concentrations did not correlate with the functional activity of any of the clotting factors. The presence of a correlation between plasma cholesterol concentrations and factor VII activity for blood samples collected at four-hour intervals suggests that plasma cholesterol concentrations may have a more acute effect on factor VII activity. Temporal variations in plasma vitamin K concentrations indicate that a single time point measurement may be an inappropriate method of establishing vitamin K status in an individual.
authors.affiliation: Wolfson Unit of Clinical Pharmacology, University of Newcastle, Newcastle upon Tyne, United Kingdom. farhad.kamali@ncl.ac.uk
authors.forename: F
authors.initials: F
authors.lastname: Kamali
authors.forename: C
authors.initials: C
authors.lastname: Edwards
authors.forename: P
authors.initials: P
authors.lastname: Wood
authors.forename: H A
authors.initials: HA
authors.lastname: Wynne
authors.forename: P
authors.initials: P
authors.lastname: Kesteven
mesh_terms: D000328:Adult; D001777:Blood Coagulation / Q000502:physiology; D001779:Blood Coagulation Factors / Q000378:metabolism*; D002784:Cholesterol / Q000097:blood; D008078:Cholesterol, LDL / Q000097:blood; D002940:Circadian Rhythm / Q000502:physiology*; D005164:Factor IX / Q000378:metabolism; D005167:Factor VII / Q000378:metabolism; D005170:Factor X / Q000378:metabolism; D005260:Female; D006801:Humans; D008055:Lipids / Q000097:blood*; D008075:Lipoproteins, HDL / Q000097:blood; D008297:Male; D011516:Prothrombin / Q000378:metabolism; D014280:Triglycerides / Q000097:blood; D014812:Vitamin K / Q000097:blood*
chemical_list: D001779:Blood Coagulation Factors; D008078:Cholesterol, LDL; D008055:Lipids; D008075:Lipoproteins, HDL; D014280:Triglycerides; D014812:Vitamin K; D005167:Factor VII; D011516:Prothrombin; D005164:Factor IX; D005170:Factor X; D002784:Cholesterol