prothrombin time test


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prothrombin time test

n.
A method for determining prothrombin time. Also called prothrombin test.

prothrombin

a glycoprotein present in the plasma that is converted into thrombin by extrinsic thromboplastin during the second stage of blood clotting; called also clotting factor II.

prothrombin consumption test
determines thromboplastin generating capacity, which provides information about the first stage of coagulation. When clotting of a normal blood sample occurs, prothrombin is converted to thrombin, thus there should be little or no prothrombin in the serum after the clot is formed. If, however, there is deficiency of blood coagulation, some of the prothrombin will not be utilized (consumed). Abnormal results of the test are found in deficiencies of the first-stage factors of coagulation (factors VIII and IX), and in the presence of circulating anticoagulants, thrombocytopenia, and any other condition leading to inadequate generation of thromboplastin. Called also serum clot time.
prothrombin converting activity
the step in blood coagulation in which factor Xa, together with factor V react with phospholipid in the presence of calcium, activates prothrombin to form thrombin.
prothrombin deficiency
prothrombin time test
a test to measure the activity of clotting factors V, VII and X, prothrombin and fibrinogen. Deficiency of any of these factors leads to a prolongation of the one-stage prothrombin times, as will circulating anticoagulants that are active against factors V, VII, or against thromboplastin. Called also pro-time.
The one-stage (OSPT) test is performed by measuring the time required for clot formation after tissue extract and calcium are added to citrated plasma. Called also Quick's prothrombin test. A two-stage test determines plasma levels of prothrombin by finding the dilution of plasma that clots a standard fibrinogen reagent in a set period of time.
References in periodicals archive ?
One manufacturer has developed a prothrombin time test using a device with unit-use cartridges that include OBCs.
Finally, they should provide a table indicating the relationship between the conventional terms for expression of prothrombin time test results and the INRs.