Editing Prothrombin time (section)

{{Short description|Blood test that evaluates clotting}}
{{cs1 config|name-list-style=vanc}}
{{Use dmy dates|date=January 2015}}
{{Infobox interventions |
  Name        = Prothrombin time |
  Image       = Fibrin-nach-Thromboplastin.jpg |
  Caption     = Blood plasma after the addition of tissue factor. The gel-like structure is strong enough to hold a steel ball. |
  ICD10       = |
  ICD9        = |
  MeshID      = D011517 |
  OtherCodes  = |
}}

The '''prothrombin time''' ('''PT''') – along with its derived measures of '''prothrombin ratio''' ('''PR''') and '''international normalized ratio''' ('''INR''') – is an [[assay]] for evaluating the [[Coagulation#Extrinsic pathway|extrinsic pathway]] and [[Coagulation#Common pathway|common pathway]] of [[coagulation]]. This [[blood test]] is also called ''protime INR'' and ''PT/INR''. They are used to determine the [[Thrombophilia|clotting tendency]] of blood, in conditions such as the measure of [[warfarin]] dosage, liver damage (cirrhosis), and [[vitamin K]] status. PT measures the following [[Coagulation#Coagulation factors|coagulation factors]]: [[fibrinogen|I (fibrinogen)]], [[thrombin|II (prothrombin)]], [[Factor V|V (proaccelerin)]], [[Factor VII|VII (proconvertin)]], and [[Factor X|X (Stuart–Prower factor)]].

PT is often used in conjunction with the [[partial thromboplastin time|activated partial thromboplastin time]] (aPTT) which measures the [[Coagulation#intrinsic pathway|''intrinsic'' pathway]] and common pathway of coagulation.{{cn|date=November 2023}}