Lupus anticoagulant (LA) is an autoimmune disorder characterized by the presence of antibodies that target phospholipid-binding proteins. Despite its name, LA is associated with an increased risk of blood clots, without bleeding. Clinical symptoms and complications of lupus anticoagulant include:

Thrombosis: Venous Thrombosis: Deep vein thrombosis (DVT), pulmonary embolism.

Arterial Thrombosis: Stroke, transient ischemic attack (TIA), myocardial infarction.

Pregnancy Complications: Recurrent miscarriages, Intrauterine growth restriction and stillbirth.

Thrombocytopenia: Low platelet count which may or may not be symptomatic.

Livedo Reticularis: A mottled, purplish discoloration of the skin.

Neurological Symptoms: Migraine, Seizures.

Cardiovascular Issues: Heart valve abnormalities.

These symptoms arises because lupus anticoagulant which increases the risk of clot formation in both veins and arteries leading to various complications. Regular monitoring and anticoagulant therapy may be necessary to manage and reduce the risk of these complications.

Clinical investigation for lupus anticoagulant involves a series of laboratory tests to detect the presence of antiphospholipid antibodies which are responsible for the condition. These tests are typically performed when a patient has a history of unexplained thrombosis, recurrent miscarriages or other clinical symptoms suggestive of antiphospholipid syndrome (APS). The key steps in the clinical investigation includes:

Patient History and Physical Examination:

Thrombotic History: Assess for history of deep vein thrombosis (DVT), pulmonary embolism or arterial thrombosis.

Pregnancy Loss: Document history of recurrent miscarriages or other pregnancy complications.

Symptoms: Check for signs like livedo reticularis, neurological symptoms or unexplained prolonged aPTT.

Screening Tests: Activated Partial Thromboplastin Time (aPTT): Prolonged aPTT that doesn’t correct with mixing studies suggests the presence of lupus anticoagulant.

Dilute Russell Viper Venom Test (dRVVT): More specific for lupus anticoagulant as it directly assesses the pathway which is affected by the antibody.

Kaolin Clotting Time (KCT): Measures clotting time which may be prolonged in the presence of lupus anticoagulant.

Confirmatory Tests: Mixing Studies. The patient’s plasma is mixed with normal plasma to see if the prolonged aPTT corrects. Lack of correction indicates the presence of an inhibitor like lupus anticoagulant.

dRVVT Confirmatory Test: A confirmatory step following the initial dRVVT, involving adding excess phospholipids to see if the clotting time shortens, which would confirm the presence of lupus anticoagulant.

Additional Antiphospholipid Antibody Tests

Anticardiolipin Antibodies: IgG and IgM antibodies tested by ELISA. Elevated levels support the diagnosis of APS.

Anti-β2 Glycoprotein I Antibodies: Also tested using ELISA. High levels indicate an increased risk for thrombotic events.

Repeat Testing: To confirm the diagnosis, positive results for lupus anticoagulant and other antiphospholipid antibodies should be repeated after 12 weeks to rule out transient causes.

Coagulation Factor Assays: To rule out other causes of prolonged clotting times or abnormal results.

Imaging Studies: Doppler Ultrasound- Used to detect DVT.

CT or MRI: May be used to identify clots in the lungs, brain, or other areas.

Other Tests: Complete Blood Count – To check for thrombocytopenia or other hematologic abnormalities.

 Interpretation of Results

Positive for Lupus Anticoagulant – Requires a comprehensive assessment, including correlation with clinical symptoms and risk factors for thrombosis.

Negative for Lupus Anticoagulant- Does not completely rule out antiphospholipid syndrome if other antiphospholipid antibodies are present.

USHA SASI
FACULTY HEMATOLOGY