Noun
a protein in blood plasma that is the inactive precursor of thrombin
Source: WordNetSeveral of the conotoxins contain two to five Gla residues. citation Methods of assessment Vitamin K status can be assessed by: * The prothrombin time (PT) test measures the time required for blood to clot. Source: Internet
This test is insensitive to mild deficiency, as the values do not change until the concentration of prothrombin in the blood has declined by at least 50%. Source: Internet