Factor V Deficiency

Excerpt

Factor V deficiency, also known as Owren disease or parahemophilia, is a rare type of bleeding disorder that can be either inherited or acquired. Dr. Paul Owren first identified it in Norway in 1943. The disease manifests itself similarly to other factor deficiencies, with symptoms ranging from minor mucosal bleeding to severe and life-threatening hemorrhages. According to the literature, the severity of bleeding generally correlates to factor Va) levels; however, some patients experience mild bleeding symptoms even with factor Va levels below 1%. Factor V deficiency can be categorized into mild, moderate, or severe based on the percentage of factor V in the plasma (>10%, 1 to 10%, <1%, respectively).

Initial laboratory values show a prolonged prothrombin time (PT) and partial thromboplastin time (aPTT) with a normal thrombin time (TT). A low plasma level of factor V can confirm the diagnosis. The distinction between inherited and acquired forms of factor V deficiency is made by mixing plasma studies. In this test, normal plasma is added to the patient's plasma which has been determined to prolong the PT and aPTT. Normalization of the PT and aPTT occurs in the case of inherited forms, as the missing factor is replaced using the normal plasma. In acquired forms, the PT and aPTT remain prolonged after the addition of normal plasma due to the presence of an inhibitor in the patient's plasma.

This test is not specific to only factor V deficiency but helps determine if the prolongation of coagulation studies results from a factor deficiency vs. an inhibitor. Treatment varies depending on whether the factor V deficiency is inherited vs. acquired. When inherited, the mainstay of treatment is to transfuse fresh frozen plasma (FFP), which provides the patient with factor V. In mild cases, antifibrinolytics may be adequate to achieve hemostasis. The mainstay of treatment for acquired factor V deficiency can be more challenging and requires control of bleeding symptoms and elimination of autoantibodies against factor V. Bleeding control is achieved with FFP, platelet transfusions, prothrombin complex concentrates, antifibrinolytics, and/or recombinant activating factor VII, whereas factor V inhibitor eradication is accomplished with immunosuppression.