Is sample collection critical for lupus anticoagulant testing?

Yes. Besides heparin contamination, other pretest variables may have a significant impact on detecting the lupus anticoagulant. The blood sample is collected in a special citrated tube and centrifuged to remove the plasma for testing. There must be the proper amount of blood in the tube and it cannot be clotted. When the blood is properly centrifuged, most of the platelets are removed from the test sample. If there are too many platelets in the plasma sample, it may be compromised (because platelets are a source of phospholipids). Also, if the patient s hematocrit is very high, test results may be affected.  more