the factor VIII activity test to help diagnose or monitor the treatment of hemophilia A. The test also can help find the reason for an abnormal result on other clotting tests, such as prothrombin time PT or partial thromboplastin time PTT. If this is not possible, make PPP within 1 hour of collection as follows: Centrifuge sample at 3600 rpm for 15 min. & transfer supernatant to a clean plastic tube. Centrifuge this supernatant again at 3600 rpm for 15 mins. & finally transfer the supernatant (PPP) to 1 labelled, clean plastic screw capped vial. FREEZE IMMEDIATELY. Ship frozen. DO NOT THAW.