Laboratory assays

This section provides an overview of the coagulation assays currently in clinical use and under development to diagnose and monitor treatment effectiveness in patients with selected bleeding disorders.

Clot-based activity assays

Clot-based activity assays provide a global assessment of coagulation function and are most commonly used to assess patients with suspected bleeding abnormalities or to monitor anticoagulant therapy.

Chromogenic activity assays

Chromogenic activity assays use coloured or fluorescent substrates to quantify the level and enzymatic activity or function of specific coagulation factors.

Global assays

Global coagulation assays can be used to characterise some haemostatic disorders and to monitor the effects of treatment. Methods include viscoelastic assays, thrombin generation assays and transmittance waveform analysis, a variation on one-stage clot assays.

Inhibitor assays

Inhibitory antibodies can be quantified using the Bethesda assay. The presence of antiphospholipid antibodies can be confirmed or excluded using a lupus anticoagulant assay.

Platelet assays

Platelet assays are useful not only to diagnose bleeding diatheses attributable to platelet dysfunction, but to monitor the effect of anti-platelet medications.

Antigen-based assays

FXIII antigen assays are recommended as a second step to determine the subtype of FXIII deficiency (FXIII-A or FXIII-B deficiency) subsequent to having detected a decrease in FXIII activity.

Genetic analyses

Characterisation of the underlying molecular genetic defect for various congenital bleeding disorders can be performed in specialist laboratories.

von Willebrand factor assays

von Willebrand factor (VWF) assays are used for differential diagnosis of von Willebrand disease (VWD) and determination of VWD subtypes.