This test is a key part of the investigation for Antiphospholipid Syndrome (APS). It detects long-term (IgG) "memory" antibodies that mistakenly attack phospholipids, the "skin" of your body's cells. The presence of this antibody is a key marker for diagnosing this autoimmune condition, which is a major cause of recurrent blood clots. A simple blood draw is required. This test provides the crucial 'historical' evidence your doctor needs to understand the root cause of your symptoms.