ANTI-CARDIOLIPIN ANTIBODIES AND LUPUS ANTICOAGULANT

CLINICAL UTILITY:

In some rheumatic diseases, particularly SLE, and in certain chronic infectious conditions like syphilis, patients develop antibodies to the heart muscle phospholipid, cardiolipin. Recent studies indicate that high levels of the antibody may occur in the serum of approximately 60% of SLE patients. Anti-cardiolipin antibodies also are found in other conditions which gove falsepositive results on the VDRL test for syphilis, since cardiolipin is part of the antigen in the serological tests for syphilis. These is also an association between anti-cardiolipin antibodies and multiple spontaneous abortions (miscarriages), and between the antibodies and lupus-like syndromes in which the patient's ANA is either positive or negative. Anticardiolipin antibodies occur also in patients with arterial and venous thrombosis, pulmonary embolism and thrombocytopenia.

The test for antibodies to cardiolipin is also useful in determining the presence of lupus anticoagulant (lupus inhibitor), which is seen in 5-10% of SLE patients. Lupus anticoagulant is a circulating antibody, which is directed against the phospholipid coagulation activator complex. Patients with this inhibitor often have a prolonged partial thromboplastin time (PTT), and sometimes a prothrombin time (PT). However, they generally do not have abnormal bleeding, but the inhibitor may be associated with thrombosis. With corticosteroid treatment, serum levels of the inhibitor tend to fall.

SPECIMEN REQUIREMENTS:

2.0 ml serum. Freeze.