Lupus Anticoagulant (SCREEN)

A positive lupus anticoagulant test means you have antiphospholipid antibodies that increase the risk of abnormal blood clots, even though they can prolong clotting tests in the lab. It’s linked to antiphospholipid syndrome, recurrent pregnancy loss, and thrombosis. Repeat testing after 12 weeks confirms persistence. Management and need for anticoagulation depend on clinical history and require specialist review.

Screening for lupus anticoagulant begins with clotting assays (dilute Russell viper venom time and/or aPTT/KCT). If prolonged, perform mixing studies to distinguish inhibitor from factor deficiency, then a confirmatory phospholipid‑neutralization test (high‑phospholipid or hexagonal‑phase) to show phospholipid dependence. Use normalized ratios. Test concurrently for anticardiolipin and anti–β2‑glycoprotein I antibodies and repeat positives after ≥12 weeks; anticoagulants can interfere.

There isn’t a single numeric “normal” for lupus anticoagulant; labs use clotting assays (e.g., dRVVT and aPTT‑based tests) and report screen/confirm ratios. Generally, a ratio ≤1.2–1.3 is considered negative (normal), while ratios above the lab’s cut‑off indicate presence of lupus anticoagulant. Positive results require confirmation and repeat testing, often after 12 weeks, before diagnosis.

Antiphospholipid antibodies are immune proteins that target phospholipid‑binding proteins (like beta‑2 glycoprotein I and cardiolipin). In pregnancy they increase risk of blood clots and placental problems, causing recurrent miscarriage, stillbirth, preeclampsia and fetal growth restriction. Diagnosis needs persistent positive tests (anticardiolipin, anti‑β2GPI or lupus anticoagulant). Treatment often includes low‑dose aspirin and heparin with close monitoring.

Lupus treatment is individualized to control symptoms, prevent flares, and limit organ damage. First-line therapy often includes hydroxychloroquine plus sun protection and lifestyle measures. NSAIDs and short-course corticosteroids treat pain and flares; immunosuppressants (azathioprine, methotrexate, mycophenolate) and biologics (belimumab, rituximab) are used for moderate-to-severe or organ‑threatening disease. Regular monitoring and vaccination are important.

Early warning signs of lupus often include persistent fatigue, unexplained fevers, and new joint pain or swelling. Characteristic findings are a butterfly facial rash and increased sensitivity to sunlight. Other early features include mouth or nasal ulcers, hair loss, Raynaud’s (cold, discolored fingers), chest pain on deep breathing, swollen lymph nodes, and unexplained weight or cognitive changes. Symptoms can come and go.