Laboratory Evaluation

Laboratory Evaluation

The initial evaluation includes the prothrombin time (PT) and partial thromboplastin time (PTT), both of which will be prolonged.

If an inhibitor is suspected, its presence should be confirmed with a mixing study and the inhibitor titer should be determined with a Bethesda assay. Factor V activity is measured by a prothrombin clot assay. Normal ranges are laboratory specific and age dependent.

As with many other bleeding disorders, evaluation for acute events depends upon the clinical symptoms. In cases of suspected intracranial hemorrhage, head CT is often appropriate for initial evaluation.