Cardiolipin antibody IgG and IgM are autoimmune antibodies directed against cardiolipin, a phospholipid in cell membranes. Their presence—especially persistent, high titers—is linked to antiphospholipid syndrome, increasing risk of arterial and venous thrombosis, recurrent miscarriage, and other clotting complications. Levels can be transient after infection or drugs; diagnosis requires blood testing and repeat positive results after 12 weeks, with management based on clotting history.

High cardiolipin IgM indicates antiphospholipid antibodies that can increase risk of blood clots (venous or arterial), recurrent pregnancy loss and other pregnancy complications. It may be transient after infection, so testing is usually repeated after about 12 weeks to confirm persistence. Management depends on symptoms — anticoagulation for thrombosis and specialist-guided aspirin/heparin in pregnancy. See a clinician for follow-up.

A positive IgM indicates a recent or current infection (early immune response), while a positive IgG indicates past exposure or later-stage immunity. When both IgM and IgG are positive, it usually means a recent infection that is progressing toward a longer-term immune response. Interpretation depends on timing, the specific disease and test accuracy; clinical correlation and follow-up testing are often recommended.

A positive anti‑cardiolipin antibody indicates the immune system is making antiphospholipid antibodies linked to antiphospholipid syndrome (APS). It increases risk of blood clots, recurrent miscarriage, stroke and other vascular events. Single positives can be transient (infection or medication); diagnosis needs persistent positivity on repeat testing (usually ≥12 weeks) plus clinical findings. Management depends on clot history and may include anticoagulation.

Cardiolipin antibodies are linked primarily to antiphospholipid syndrome — causing arterial/venous thrombosis and recurrent pregnancy loss — and to systemic lupus erythematosus. They also appear in other autoimmune diseases (e.g., rheumatoid arthritis, Sjögren’s), certain infections (syphilis, HIV, hepatitis C), some malignancies, and occasionally after medications or transient infections. Presence prompts evaluation for clotting and pregnancy risk.

Antibodies most characteristically elevated in systemic lupus erythematosus are anti–double‑stranded DNA (anti‑dsDNA), which correlate with disease activity and lupus nephritis. Antinuclear antibodies (ANA) are positive in nearly all patients but are nonspecific. Anti‑Smith (anti‑Sm) antibodies are highly specific for lupus though less sensitive. Other autoantibodies (anti‑RNP, antiphospholipid) may also be present.