Table 3.

Effect of Lupus Anticoagulants and Anticoagulant Therapies on Commonly Used Clinical Laboratory Assays (adapted from reference (81))^*

Laboratory Test	Lupus Anticoagulant	Therapeutic UFH	Therapeutic LMWH	Therapeutic Fondaparinux	Vitamin K Antagonists	Direct thrombin inhibitors†	Direct Factor Xa inhibitors‡
PT	Normal or prolonged	Normal to mild prolongation	Normal	Normal	Prolonged	Variable prolongation	Variable prolongation
aPTT	Typically prolonged	Prolonged	Mild prolongation	Normal to minimal prolongation	Normal to mild prolongation	Prolonged	Variable prolongation
TCT	Normal	Prolonged	Variable prolongation	Normal	Normal	Prolonged	Normal
dRVVT (screening step)	Typically prolonged	Prolonged^	Variable effect	Normal	Prolonged	Prolonged**	Prolonged††
Mixing study of prolonged screening test	No correction	No correction	No correction	Typically not applicable	Correction	No correction	No correction
Anti-factor Xa assay‡‡	Normal	Elevated	Elevated	Elevated	Normal	Normal	Elevated

^*The column for lupus anticoagulant test results represents what would be expected for a plasma sample with no anticoagulant therapy, and the columns for the anticoagulant therapies represent what would be expected for plasma samples with each of the classes of anticoagulants in the absence of a lupus anticoagulant. A plasma sample from a patient with a lupus anticoagulant and one (or more) of the anticoagulant agents would have test results reflecting the combined presence of more than one variable. Abbreviations used include: PT, prothrombin time; aPTT, activated partial thromboplastin time; TCT, thrombin clotting time; dRVVT, dilute Russell's viper venom time; UFH, unfractionated heparin; LMWH, low-molecular weight heparin.

^†Direct thrombin inhibitors include the parenteral agents lepirudin, argatroban, bivalirudin, and desirudin, and the oral agent dabigatran.

^‡Direct factor Xa inhibitors include rivaroxaban, apixaban, and edoxaban. Relatively limited data are available on the latter two agents.

^{^}Although unfractionated heparin will typically prolong the dRVVT, most commercially available dRVVT reagents contain a heparin neutralizer that neutralizes up to or slightly greater than 0.8 to 1.0 IU/mL UFH present in patient plasma.

^**Results are for lepirudin, argatroban, and bivalirudin; no data are available for desirudin or dabigatran etexilate.

^††Results are for rivaroxaban only.

^‡‡A ‘normal’ result indicates no evidence for anti-factor Xa activity in the plasma sample being tested, whereas an ‘elevated’ result indicates the presence of anti-factor Xa activity (antithrombin-dependent or independent).