Home Biomarkers Lupus Anticoagulant

Lupus Anticoagulant

Blood clotting Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Blood clotting

Overview

Lupus anticoagulant (LA) is not a single molecule but a group of antiphospholipid antibodies that interfere with phospholipid-dependent clotting tests in the laboratory. The test detects these antibodies using clotting assays (eg, dilute Russell viper venom time [dRVVT], and aPTT-based assays) and reports whether an inhibitor consistent with LA is present. Clinically LA is associated with an increased risk of arterial and venous thrombosis and with pregnancy complications (recurrent miscarriages, stillbirth). Test is indicated for unexplained thrombosis, recurrent pregnancy loss, or an unexplained prolonged clotting time. Prevalence and interpretation vary with age, sex and comorbid autoimmune disease (more frequent in women and in people with systemic lupus erythematosus).

People also test for

Test Preparation

Overnight fasting is preferred but not mandatory
A duly filled coagulation requisition form (Annexure - CR/05) is mandatory for sample collection
Kindly provide complete clinical details and medication history or doctor's prescription
this information is important for correlation of your test results

Why Do I Need This Test

Profile: Blood clotting (coagulation) / thrombophilia workup - Symptoms: Unexplained deep vein thrombosis, pulmonary embolism, arterial clots (stroke), recurrent miscarriages, or unexplained prolonged aPTT - Conditions diagnosed/monitored: Antiphospholipid syndrome (APS), thrombotic risk stratification in autoimmune disease - Reasons for abnormal result: Presence of antiphospholipid antibodies, acute infection, certain drugs, or anticoagulant therapy - Biological meaning: Positive test indicates a phospholipid-dependent inhibitor that increases thrombotic risk despite prolonging clotting tests - Lifestyle/family history: Smoking, oral contraceptives, pregnancy, family history of thrombosis or autoimmune disease may prompt testing

Run our symptom checker to see if this test is right for you

Symptom Checker

Understanding Test Results

A dRVVT or aPTT normalized ratio below ~1.2 is considered negative for lupus anticoagulant.
Ratios around 1.2–1.5 are often reported as borderline/indeterminate and warrant repeat testing and confirmatory steps (mixing studies and phospholipid neutralization).
Ratios >1.5 (or above the laboratory’s specified cutoff) are usually considered positive and suggest the presence of LA; higher values imply a stronger inhibitor.
A single positive result increases suspicion for antiphospholipid antibodies but is not diagnostic of antiphospholipid syndrome (APS) persistence on repeat testing at least 12 weeks apart plus clinical criteria (thrombosis or pregnancy morbidity) is required for diagnosis.
False positives can occur with heparin, direct oral anticoagulants, warfarin, acute infections, or elevated C-reactive protein; negative tests do not exclude APS if other antiphospholipid antibodies (anticardiolipin or anti–β2‑glycoprotein I) are present.
Positive LA indicates increased thrombotic risk and usually prompts specialist referral for risk management.

Normal Range

dRVVT ratio: <1.2 (ratio) OR aPTT normalized ratio: <1.2 (ratio)

FAQs

Q: What are the symptoms of lupus anticoagulant?

A: Lupus anticoagulant often causes no symptoms but increases risk of blood clots. Signs include deep vein thrombosis (leg swelling/pain), pulmonary embolism (shortness of breath, chest pain), arterial events (stroke, TIAs), recurrent miscarriages or stillbirth, pregnancy complications (preeclampsia), livedo reticularis (mottled skin), low platelet counts, and abnormal clotting tests such as a prolonged aPTT.

Q: Is lupus anticoagulant life threatening?

A: Lupus anticoagulant is an antibody that raises the risk of dangerous blood clots, leading to deep vein thrombosis, pulmonary embolism, stroke, or pregnancy loss. By itself it may be asymptomatic, but if it triggers thrombosis it can be life‑threatening. People with the antibody—especially those with prior clots or antiphospholipid syndrome—may need anticoagulation and close monitoring to reduce risk.

Q: Is lupus a clotting disorder?

A: Lupus is an autoimmune inflammatory disease, not primarily a clotting disorder. However, people with lupus have a higher risk of blood clots. Antiphospholipid syndrome antibodies that often occur with lupus causes a true hypercoagulable state and recurrent arterial or venous thromboses. Inflammation, medications and immobility also raise clot risk, so testing for antiphospholipid antibodies guides prevention and treatment.

Q: Why does lupus anticoagulant cause miscarriage?

A: Lupus anticoagulant is an antiphospholipid antibody that promotes blood clotting by interfering with clot-regulating proteins, activating endothelium and complement. In pregnancy it causes placental thrombosis, infarction and impaired blood flow, producing placental insufficiency, fetal growth restriction and recurrent miscarriage or stillbirth. Early detection and anticoagulant treatment can reduce risk.

Q: How does a person get lupus anticoagulant?

A: A person develops lupus anticoagulant when the immune system makes antiphospholipid antibodies that alter clotting tests and increase clot risk. It can arise with autoimmune diseases (notably systemic lupus), certain infections, some medications, malignancy, or without a clear cause. It may be transient after infection or persistent, and diagnosis requires specific blood tests repeated over time.

Q: Does lupus cause weight gain?

A: Lupus itself doesn’t usually directly cause weight gain, but weight gain is common in people with lupus. Reasons include long‑term corticosteroid treatment (increased appetite, fluid retention, fat redistribution), reduced activity from pain and fatigue, and some other medications. Managing medications, diet, graded exercise, and discussing concerns with your clinician or a dietitian can help control weight and metabolic risks.