The Beta-2 Glycoprotein 1 IgM test is an immunoassay that detects IgM-class autoantibodies targeting beta-2 glycoprotein 1, a plasma protein involved in coagulation regulation. Elevated levels of these antibodies are strongly associated with Antiphospholipid Syndrome (APS), an autoimmune disorder predisposing individuals to recurrent blood clots (thrombosis) in arteries and veins, as well as pregnancy complications. While IgG is the primary isotype linked to APS, measuring IgM provides crucial supplementary diagnostic information, particularly in patients who are IgG-negative but exhibit strong clinical symptoms of APS. It aids in risk stratification and comprehensive diagnostic evaluation.