Factor IX (Antihemophilic B) Activity

To help determine if the level of factor IX coagulation factor is elevated, decreased or normal.

When there is an unexplained bleeding or prolonged bleeding when prothrombin time (PT) or activated partial thromboplastin time (PTT) test results are abnormal, when there is a family history of coagulation factor deficiency (hereditary), and to monitor the severity of factor deficiency or to know the effectiveness of treatment.