What is ACA-IgM? ACA-IgM, also known as Anti-Cardiolipin Antibody IgM, is a blood test used to detect IgM antibodies directed against cardiolipin, a type of phospholipid found in cell membranes. The presence of these antibodies may indicate autoimmune activity in the body, particularly related to antiphospholipid syndrome (APS). This test is often performed as part of a broader...