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 ?
Outsourcing prothrombin time tests was risking both legal liability and patient health.
Patients on these drugs should be monitored with prothrombin time tests, however, and we used outpatient bills for these tests within the first 30 days of discharge as a proxy for warfarin use.
The outcome variables, all dichotomous, were use of noninvasive tests within 30 days of admission (for all TIA patients, n = 17,437); cerebral angiography within 30 days of admission (estimated only for those patients who received noninvasive tests, n = 8,203); carotid endarterectomy within 30 days of admission (estimated only for those patients who received angiography, n = 1,306); anticoagulant therapy, as proxied by outpatient prothrombin time tests within 30 days of discharge (estimated only for those patients with a secondary diagnosis of atrial fibrillation and without contraindications, n = 1,568); and a neurologist as attending physician (estimated for all TIA patients).
It has the potential to cut the number of prothrombin time tests that we do by more than 90%.
In reading your May 2001 article, "Finding control in quality control of unit-use prothrombin time tests," I found your insights to be very much on target.
One involves two prothrombin time tests that were cleared by the FDA for prescription home use and received a CLIA waiver from the Centers for Disease Control & Prevention.

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