The antiphospholipid antibody test detects antibodies (lupus anticoagulant, anticardiolipin, anti–beta2‑glycoprotein I) associated with antiphospholipid syndrome. It’s used for unexplained blood clots, recurrent miscarriages, stroke at a young age, or abnormal clotting tests. Positive results, usually repeated after 12 weeks, help confirm diagnosis and guide treatment and anticoagulation to lower future clotting or pregnancy risk.

The APA IgM test detects IgM-class antiphospholipid antibodies in the blood. It helps evaluate for antiphospholipid syndrome, which raises risk of blood clots and recurrent pregnancy loss. A single positive result can be transient (infection or medication), so confirmation is recommended about 12 weeks later and in conjunction with other tests (IgG antiphospholipid antibodies and lupus anticoagulant) and clinical findings.

Antiphospholipid antibodies are characteristic of antiphospholipid syndrome (APS), an autoimmune condition that causes blood clots and pregnancy complications. They often occur secondary to systemic lupus erythematosus (SLE) but can also appear transiently after infections, with certain drugs, or alongside other autoimmune diseases and malignancies. Diagnosis requires persistent positive tests plus clinical features such as thrombosis or recurrent pregnancy loss.

The three antiphospholipid antibodies in APLA (antiphospholipid) syndrome are lupus anticoagulant, anticardiolipin antibodies, and anti–beta‑2 glycoprotein I antibodies. These autoantibodies are identified by specific blood tests and are associated with an increased risk of venous and arterial thrombosis and pregnancy complications. Diagnosis typically requires persistently positive tests at least 12 weeks apart.

In systemic lupus erythematosus (SLE), antinuclear antibodies (ANA) are commonly elevated; the most characteristic is anti–double‑stranded DNA (anti‑dsDNA), often high and correlating with disease activity and kidney involvement. Anti‑Smith (anti‑Sm) antibodies are specific for SLE but less frequent. Rising anti‑dsDNA levels can signal a flare and help guide treatment decisions alongside clinical assessment and other tests.

Lupus (systemic lupus erythematosus) is a systemic autoimmune disease causing inflammation and organ damage—skin rashes, joint pain, fatigue, kidney or brain involvement. Antiphospholipid syndrome (APS) is an autoimmune clotting disorder where antiphospholipid antibodies cause recurrent arterial or venous clots and pregnancy loss. APS can be primary or occur secondary to lupus; lupus is multisystem inflammation, APS is mainly hypercoagulability.