scope:

This Standard is applicable to the determination of the thromboplastin (prothrombin) time (PT) using plasma from citrated venous blood (sample).

The determination of thromboplastin (prothrombin) time is used:

a) for monitoring the influence of pharmacotherapy on blood coagulation, especially in the case of treatment with vitamin K antagonists;

b) as a global test for the exogenous system of blood coagulation (for fibrinogen, and the factors II, V, VII und X) and for the evaluation of the synthesis function of the liver.

The PT may not be used for the surveillance of the pharmacotherapeutic influence of blood coagulation by direct oral thrombin inhibitors or factor Xa-inhibitors (e.g., Dabigatran, Rivaroxaban, Apixaban, Edoxaban).

When determining thromboplastin (prothrombin) times by the procedure described in this standard, the results are only comparable if qualitatively similar thromboplastins are used.

NOTE "Qualitatively similar" means similar sensitivity to coagulation and anticoagulant factors.