Dr. med. Dirk Manski

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Prothrombin time (PT)

Screening test of the extrinsic plasmatic coagulation cascade, in particular factor I, II, V, VII und X. In addition, therapy with warfarin and phenprocoumon can be monitored with PT. For better comparability of different laboratories, the prothrombin time is given as an international normalized ratio (INR).

Standard value:

INR 0,9--1,25.

Laboratory test method:

Ball coagulometer.


Screening test for coagulation disorders, treatment with warfarin or phenprocoumon, evaluation of liver function.

Differential Diagnosis of Prolonged PT

A prolonged PT equals a higher INR.

Differential Diagnosis of shortened PTT

Activation of the coagulation system due to traumatic venipuncture or acute-phase-response.

Index: 1–9 A B C D E F G H I J K L M N O P Q R S T U V W X Y Z


Guder, W. G. & Nolte, J.
Das Laborbuch für Klinik und Praxis
Urban + Fischer, 2009

Siegenthaler 1988 SIEGENTHALER, W. ; SIEGENTHALER, W. (Hrsg.):
Differentialdiagnose innerer Krankheiten.
Georg Thieme Verlag, Stuttgart, New York., 1988

  Deutsche Version: Gerinnungstest PTT