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Human Phenotype Ontology
Preferred Name | Prolonged prothrombin time | |
Synonyms |
Increased INR Prolonged PT Low factor II activity Reduced factor II activity increased international normalised ratio Increased international normalised ratio Increased international normalized ratio Reduced prothrombin activity |
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Definitions |
Increased time to coagulation in the prothrombin time test, which is a measure of the extrinsic pathway of coagulation. The results of the prothrombin time test are often expressed in terms of the International normalized ratio (INR), which is calculated as a ratio of the patient's prothrombin time (PT) to a control PT standardized for the potency of the thromboplastin reagent developed by the World Health Organization (WHO) using the formula: INR is equal to Patient PT divided by Control PT. The prothrombin time (PT) and the activated partial thromboplastin time (APTT) are the most requested tests to investigate patients with congenital or acquired coagulopathies and drug monitoring. They are defined as the time (seconds) needed to clot platelet-poor plasma upon addition of coagulation triggers, such as tissue factor in complex with phospholipids and calcium chloride (in the PT), or negatively charged phospholipids-activators and calcium chloride (in the APTT). They can hence be considered as global coagulation tests sensitive to deficiencies of many coagulation factors. In brief, they are both sensitive to factor X, V, II and fibrinogen, whereas the PT is only sensitive to factor VII deficiency and the APTT is sensitive to pre-kallikrein, high molecular weight kininogen (HMWK), factor XII, XI, IX and VIII deficiencies. Normal plasma in the PT clots approximately within 10-12 s upon triggering coagulation, and the normal reference range is (usually) narrow. PT results have been reported as clotting time, percentage activity, PT-ratio (patient-to-normal clotting time) and as international normalized ratio (INR). The INR scale has been devised to harmonize results stemming from different thromboplastins from patients on treatment with vitamin K antagonists. Some recommend abandoning the approach of using percentage activity to assess PR. |
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ID |
http://purl.obolibrary.org/obo/HP_0008151 |
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comment |
The prothrombin time (PT) and the activated partial thromboplastin time (APTT) are the most requested tests to investigate patients with congenital or acquired coagulopathies and drug monitoring. They are defined as the time (seconds) needed to clot platelet-poor plasma upon addition of coagulation triggers, such as tissue factor in complex with phospholipids and calcium chloride (in the PT), or negatively charged phospholipids-activators and calcium chloride (in the APTT). They can hence be considered as global coagulation tests sensitive to deficiencies of many coagulation factors. In brief, they are both sensitive to factor X, V, II and fibrinogen, whereas the PT is only sensitive to factor VII deficiency and the APTT is sensitive to pre-kallikrein, high molecular weight kininogen (HMWK), factor XII, XI, IX and VIII deficiencies. Normal plasma in the PT clots approximately within 10-12 s upon triggering coagulation, and the normal reference range is (usually) narrow. PT results have been reported as clotting time, percentage activity, PT-ratio (patient-to-normal clotting time) and as international normalized ratio (INR). The INR scale has been devised to harmonize results stemming from different thromboplastins from patients on treatment with vitamin K antagonists. Some recommend abandoning the approach of using percentage activity to assess PR.
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database_cross_reference |
SNOMEDCT_US:409674002 UMLS:C0151872
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definition |
Increased time to coagulation in the prothrombin time test, which is a measure of the extrinsic pathway of coagulation. The results of the prothrombin time test are often expressed in terms of the International normalized ratio (INR), which is calculated as a ratio of the patient's prothrombin time (PT) to a control PT standardized for the potency of the thromboplastin reagent developed by the World Health Organization (WHO) using the formula: INR is equal to Patient PT divided by Control PT.
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has_alternative_id |
HP:0012201
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has_exact_synonym |
Increased INR Prolonged PT Low factor II activity Reduced factor II activity increased international normalised ratio Increased international normalised ratio Increased international normalized ratio Reduced prothrombin activity
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has_obo_namespace |
human_phenotype
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id |
HP:0008151
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label |
Prolonged prothrombin time
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notation |
HP:0008151
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prefLabel |
Prolonged prothrombin time
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subClassOf |
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