부산대학교 도서관

Prothrombin time (PT) and activated partial thromboplastin time (APTT) are important screening tests that are used in the laboratory evaluation of patients suspected of having congenital or acquired alterations of the coagulative phase of hemostasis, including the presence of coagulation inhibitors. PT explores the extrinsic pathway and the common pathway of the coagulation system and is also the test of choice to monitor the efficacy and safety of oral anticoagulant therapy with anti-vitamin K (VKA) drugs. APTT explores the intrinsic pathway and the common pathway of coagulation and is also used in monitoring unfractionated heparin therapy. How to communicate the results of these tests in the laboratory report is still a source of debate today and many possibilities have been proposed: seconds, prothrombin activity, ratio [the ratio between the coagulation time of the plasma under test and the Mean Normal Prothrombin Time (MNPT)] and INR (International Normalized Ratio) for PT, seconds and ratio for APTT. As with all laboratory tests, it is necessary that the results of these tests are communicated clearly, with a single value, to allow a correct and unambiguous interpretation of the tests by the requesting clinicians. The use of multiple results for both tests can be confusing and contradictory in some cases and can lead to incorrect interpretations of the tests. Aim of this document is to make proposals to harmonize the laboratory report of these tests. For PT, it is recommended to use the ratio for patients who are not on anticoagulant treatment with VKA and the INR for patients who are on VKA treatment. For APTT, there is only one correct way of reporting the test results, which is represented by the ratio. Both tests, PT and APTT, must not be used to monitor the Direct Oral Anti-Coagulants (DOACs) therapy; for these tests, the use of specific tests is necessary. [ABSTRACT FROM AUTHOR]