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Partial thromboplastin time (PTT)

Screening test of the intrinsic plasmatic coagulation cascade, in particular factor I, II, V, VIII-XII. In addition, therapy with unfractionated heparin can be monitored with PTT. The effect of low molecular weight heparins is not detected by PTT.

Standard value:

Depending on reagent and laboratory 20–40 s.

Laboratory test method:

Ball coagulometer.

Indications:

Screening test for coagulation disorders, treatment with heparin.

Differential Diagnosis of Prolonged PTT

• Congenital coagulation factor deficiency (factor I, II, V, hemophilia A, hemophilia B, X, XI), von Willebrand disease (vWD).
• Acquired factor deficiencies due to severe hepatic dysfunction, inhibitors of coagulation factors (circulating anticoagulants), antiphospholipid antibodies.
• Therapy with heparin or direct oral anticoagulants (DOAK), overdose of warfarin or phenprocoumon.

Differential Diagnosis of shortened PT

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

References

  Deutsche Version: Gerinnungstest PTT