Platelets (also known as thrombocytes) are small, round cell fragments that are vital for normal blood clotting. The platelet function test measures the ability of platelets to aggregate and promote clotting in a sample of blood. This test is used to identify and help diagnose platelet dysfunction (ex. Von Willebrand disease), monitor anti-platelet therapy, detect aspirin resistance, and to screen at-risk pre-surgical patients. Examples of inherited platelet function disorders include: Von Willebrand disease, Glanzmanns thrombasthenia, Bernard-Soulier syndrome, and storage pool disease. Acquired platelet dysfunction — those that are not inherited — may be due to chronic conditions such as: kidney failure, myeloproliferative disorders or acute leukemia. Some acquired platelet disorders that are temporary include: Decreased function due to medications like aspirin and nonsteroidal anti-inflammatory drugs, or abnormal function after prolonged cardiac bypass surgery. Platelet count is REDUCED in malignancies, cytotoxic chemotherapy, autoimmune purpura, DIC, hereditary diseases such as Wiscott-Aldrich syndrome, Fanconi’s syndrome, Chediak-Higashi anomaly and Bernard-Soulier syndrome. INCREASED count is seen in chronic haemorrhage, essential thrombocythemia, polycythemia vera, vasculitides, inflammatory disorders, and post-splenectomy.