PTT Mixing Study

This laboratory test corrects prolonged partial thromboplastin time (PTT). The patient's plasma is mixed with normal plasma (containing all clotting factors at 100% concentration). Clotting times are measured before and after mixing to determine whether the prolonged PTT is due to a deficiency in clotting factors (corrected by mixing) or to the presence of inhibitors (not corrected or only partially corrected).