LA assays

Types of LA assay/principleAssaysNon-LA causes of clotting time prolongation
Based on the intrinsic pathway

LA-sensitive routine aPTT

Dilute activated partial thromboplastin time (dAPTT)

Kaolin clotting time (KCT)

Silica clotting time (SCT)

Isolated or combined deficiencies of coagulation factors II, V, VIII, IX, X, XI, XII, prekallikrein (PK), and high molecular weight kininogen (HMWK)

Fibrinogen deficiencies

Non-phospholipid-dependent inhibitors

Therapeutic anticoagulation with vitamin K antagonist (VKA), unfractionated heparin (UFH), low molecular weight heparin (LMWH), direct thrombin inhibitor (DTI), and direct FXa inhibitor (DFXaI)

Based on the extrinsic pathway

Dilute prothrombin time (dPT)

Activated Seven Lupus Anticoagulant (ASLA) assay

Isolated or combined deficiencies of coagulation factors II, V, X; also factor VII for dPT

Fibrinogen deficiencies

Non-phospholipid-dependent inhibitors

Therapeutic anticoagulation with VKA, DTI, and DFXaI

Therapeutic anticoagulation with UFH & LMWH if neutraliser capacity exceeded

Based on the common pathway (FX activation)

dRVVT

Vipera lebetina venom time (VLVT)

Isolated or combined deficiencies of coagulation factors II, V, and X

Fibrinogen deficiencies

Non-phospholipid-dependent inhibitors

Therapeutic anticoagulation with VKA, DTI, and DFXaI

Therapeutic anticoagulation with UFH & LMWH if neutraliser capacity exceeded

Based on the common pathway (FII activation)

Taipan snake venom time (TSVT)

Textarin time

Factor II deficiency; also factor V for textarin time

Fibrinogen deficiencies

Non-phospholipid-dependent inhibitors

Therapeutic anticoagulation with UFH, LMWH, and DTI