Home Biomarkers Anti Cardiolipin IgM

Anti Cardiolipin IgM

Blood clotting Biomarker

Sample Needed

Collection Type: Blood

Body System

Related System: Blood clotting

Overview

Anti‑cardiolipin IgM are autoantibodies directed against cardiolipin, a phospholipid found on cell membranes. The test measures the IgM isotype of anticardiolipin antibodies in the blood. Persistent positive results (especially with other antiphospholipid antibodies) are associated with antiphospholipid syndrome (APS), which increases risk of arterial and venous thrombosis and pregnancy complications such as recurrent miscarriage. Testing is prompted by unexplained deep vein thrombosis, pulmonary embolism, stroke at a young age, recurrent pregnancy loss, thrombocytopenia, or features of systemic lupus erythematosus. Levels can be transiently raised after infections or certain drugs, are more clinically important when persistent (repeat testing ≥12 weeks), and are especially relevant in women of reproductive age and patients with autoimmune disease.

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Test Preparation

No special preparation is required

Why Do I Need This Test

Profile: Blood clotting / thrombophilia workup.
Symptoms indicating test: unexplained DVT/PE, arterial thrombosis (stroke/MI) at a young age, recurrent miscarriages, unexplained thrombocytopenia, livedo reticularis.
Conditions diagnosed/monitored: antiphospholipid syndrome, monitoring in SLE or recurrent pregnancy loss.
Reasons for abnormal levels: autoimmune disease (e.g., SLE), recent infections, certain medications; transient versus persistent autoantibody production.
Biological meaning of abnormal values: presence of autoantibodies that increase thrombotic and pregnancy morbidity risk.
Behaviors/lifestyle: smoking, pregnancy, oral contraceptives or estrogen therapy, and immobility raise clot risk (especially if antibodies present).
Family history: early thrombosis or autoimmune disease increases pretest concern.

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Understanding Test Results

Values <20 MPL units are considered negative/normal and carry no increased antibody-related thrombotic risk by themselves.
Low or borderline results (about 20–39 MPL) may be transient (often after infection) and have limited clinical significance unless they persist on repeat testing at ≥12 weeks.
Moderate positive titres (≈40–79 MPL) raise concern for antiphospholipid syndrome when persistent and/or accompanied by clinical events.
High titres (≥80 MPL) indicate a higher risk of recurrent thrombosis and pregnancy complications and warrant specialist assessment and consideration of long‑term anticoagulation or pregnancy management.
Isolated IgM positivity generally confers lower thrombotic risk than IgG positivity but must be interpreted with clinical history, repeat testing, and results for other antiphospholipid antibodies (anticardiolipin IgG, anti‑β2 glycoprotein I, lupus anticoagulant).
Laboratory methods and reference cutoffs vary, so interpret results in the context of the reporting lab.

Normal Range

0-20 MPL units

FAQs

Q: What does positive anti-cardiolipin IgM mean?

A: Positive anti‑cardiolipin IgM means you have antiphospholipid antibodies. This can be associated with antiphospholipid syndrome—higher risk of blood clots and pregnancy complications—but may be transient after infection or medications. Confirmation needs repeat testing after ≥12 weeks, evaluation of antibody titers, and other antiphospholipid tests; discuss findings and management with your clinician.

Q: What does it mean if my anticardiolipin is high?

A: High anticardiolipin antibodies suggest an increased risk of blood clots and are a marker of antiphospholipid antibody syndrome (APS). They’re linked to venous or arterial thrombosis and pregnancy complications (recurrent miscarriage, fetal loss). Results can be transient after infections or medications, so doctors usually repeat testing after 12 weeks and assess clot history before recommending treatments like anticoagulation or pregnancy management.

Q: What causes anti-cardiolipin antibodies?

A: Anti-cardiolipin antibodies arise most often from autoimmune conditions—particularly antiphospholipid syndrome and systemic lupus erythematosus—or occur idiopathically. They can also appear transiently after infections (such as syphilis, HIV or hepatitis), be drug-induced in rare cases, or associate with malignancies. Persistent positivity versus transient elevation determines clinical significance and risk of clotting or pregnancy complications.

Q: What is the normal range for anticardiolipin IgM?

A: Anticardiolipin IgM is reported in MPL units. Typical interpretation: <20 MPL is considered negative/normal; 20–39 MPL is low/borderline; ≥40 MPL is a moderate–high positive (clinically significant). Exact cutoffs vary by laboratory, and a persistently positive result (repeat after ≥12 weeks) is required for antiphospholipid syndrome diagnosis.

Q: Does anticardiolipin IgM increase risk of blood clots?

A: Anticardiolipin IgM can be associated with higher clot risk, but its link is weaker than anticardiolipin IgG or anti–β2‑glycoprotein I. Isolated, low‑titer IgM is often not predictive of thrombosis; persistent, moderate‑to‑high titers or multiple positive antiphospholipid antibodies confer greater risk. Repeat testing after 12 weeks and clinical correlation are needed—discuss results with your physician for individualized assessment.

Q: Can anti-cardiolipin IgM be positive due to infection or temporarily?

A: Yes. Anti‑cardiolipin IgM can be transiently positive during infections (viral or bacterial), after vaccinations, with certain drugs or other inflammatory states. A single, low‑titer IgM is often clinically insignificant. For diagnosing antiphospholipid syndrome, antibodies should be persistently positive on repeat testing at least 12 weeks apart; high titers or persistent positivity have greater clinical relevance.