<prompt> Which of the following is done for a patient on coumarin warfarin therapy:Partial thromboplastin time PTTProthrombin time PTBleeding time BTCapillary fragility test CFT  <response>: When a coumarin, such as warfarin, is given to a patient, the amounts of active prothrombin and Factors VII, IX, and X, all formed by the liver, begin to fall. Prothrombin time gives an indication of the concentration of prothrombin in the blood.The normal prothrombin time is about 12 seconds.Reference: Ganong Physiology 25th ed page no 492,493 