What is important about the test systems used for detection of the lupus anticoagulant?

a. The phospholipid concentration should be high.
b. Ellagic acid should be the PTT activator substance.
c. The patient plasma and normal plasma used for mixing studies should be platelet poor.
d. A 1:1 mix should be performed when the initial test is normal to improve the sensitivity.

ANS: C
Platelets contain phospholipid in their membrane, and this can overcome and thus mask the lupus anticoagulant when it is present. Thus both the patient and the normal plasma used for mixing studies must be platelet poor. The phospholipid concentration in the reagent used for detection must also have a low concentration of phospholipid to be sensitive. The initial test before the 1:1 mix must be prolonged to even suggest the possible presence of the lupus anticoagulant, providing a lupus anticoagulant–sensitive reagent is used.