Lupus anticoagulant (inhibitor)

Last updated: Thursday, 16, August, 2007

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4.5 mL blood added to 0.5 mL citrate.

Conventional coagulation specimen may not be suitable as the sample has to be first depleted of platelets before testing.

Indicate this test clearly on the request form so that it can be processed differently by the laboratory (that is, either double spun or filtered prior to freezing).


A number of techniques are in use including Kaolin clotting time, PT using dilute thromboplastin, dilute Russell viper venom time, platelet neutralisation procedure.


Investigation of prolonged APTT not corrected by normal plasma; SLE; unexplained recurrent fetal loss, vascular thrombosis.


Lupus inhibitors reported in 5-10% of patients with SLE, but are more commonly seen without clinical or serological evidence of SLE. They are associated with an increased risk of venous and arterial thrombosis and recurrent fetal loss.

Bleeding does not occur unless there is associated thrombocytopenia or specific coagulation factor inhibitor, or in rare cases of lupus inhibitors associated with prothrombin consumption.

See also Cardiolipin antibodies and Phospholipid antibody syndrome.


Exner T et al. Br J Haematol 1987; 17: 143-151.

Triplett DA and Brandt J. Br J Haematol 1989; 73: 139-142.

Harris EN. Br J Haematol 1990; 74: 1-10.

Monica Galli et al. Blood 2003; 101: 1827-1832