What is analysed in a lupus anticoagulant test?

The lupus anticoagulant test includes a series of tests that detect the presence of lupus anticoagulant in blood. The autoantibodies are directed against phospholipids and phospholipid-associated proteins that are found in cell membranes. These autoantibodies interfere with the coagulation process and increase the risk of blood clot formation. 

What does the result mean?

The presence of lupus anticoagulant in blood is associated with a state of blood hypercoagulability. Lupus anticoagulant interferes with the coagulation tests that are performed in the laboratory. For example, lupus anticoagulant inhibits the chemical reactions that lead to the formation of a clot in the partial thromboplastin time (PTT), a test frequently requested in the evaluation of coagulation. 

Why is this analysis carried out?

The lupus anticoagulant test is performed to evaluate the cause of a state of blood hypercoagulability, a prolongation of the partial thromboplastin time (PTT, aPTT), the presence of recurrent abortions, or as part of the evaluation of an antiphospholipid syndrome.

When is the analysis done?

It is recommended to perform the test when signs and symptoms of thrombosis or thromboembolism have occurred, when the PTT is prolonged, or when recurrent abortions have occurred. 

What sample is required?

The determination is made from a venous blood sample from the arm. No special preparation is needed for this test. 

How is it used?

There is no single test available that allows the lupus anticoagulant to be evaluated, as it cannot be measured directly. Normally the presence of lupus anticoagulant is established using a series of sequential tests that are not standardized. In the initial study, tests are performed that use phospholipid-type reagents, usually PTT, PTT-AL, or the diluted Russell viper venom time (DRVVT) test. All these tests evaluate the time (seconds) it takes the sample to form a clot.

The presence of lupus anticoagulant will prolong this time. Depending on the results of the previous tests, other studies are performed, either to confirm or rule out the presence of lupus anticoagulant.

What are the normal values?

There are no established normal values for lupus anticoagulant. The presence of lupus anticoagulant is established using a series of sequential tests that are not standardised.

What does it mean to have altered values?

The presence of lupus anticoagulant in blood is associated with a state of blood hypercoagulability.