Parahemophilia (Factor V Deficiency)

Definition

Parahemophilia or Factor V deficiency is a rare coagulation disorder. It is an inherited condition that affects the ability of the blood to clot. It also termed as Owren’s disease, proaccelerin deficiency or labile factor deficiency.

Frequency

  • No apparent racial predilection for factor V deficiency exists.
  • Factor V deficiency affects males and females with equal frequency.
  • Factor V deficiency affects all ages. The age at presentation indirectly varies with the severity of disease.
  • About 1 person in 1 million people is affected with this disease.

Causes

Parahemophilia is caused by a large number of genetic abnormalities. It follows the inheritance pattern as being autosomal recessive. In this disorder, the plasma protein Factor V is low or missing. Thus, when certain coagulation is needed the chain reaction does not take place normally. Inheriting a defective Factor V gene or acquiring an antibody that interferes with normal Factor V function also contributes to the presence of the deficiency.

Inhibitor of Factor V can be acquired in the following conditions:

  • After giving birth
  • After being treated with a certain type of fibrin glue
  • After surgery
  • With an autoimmune diseases and certain cancers

Physiology of Blood Clotting

Factor V is an essential component in the blood coagulation cascade. It is synthesized by the liver and in megakaryocytes. This plasma protein circulates in an inactive form. When coagulation is taking place, Factor V is converted to an active factor, Factor Va through a limited proteolysis by the presence of the serine protease a-thrombin. Factor together with the activated factor Xa forms the prothrombinase complex. This complex is the one responsible for the rapid conversion of zymogen prothrombin to the active serine protease a-thrombin. Thrombin cleaves fibrinogen to form fibrin, leading to the ultimate step in coagulation, the formation of a fibrin clot.

Signs and Symptoms

  • Nosebleeds
  • Bleeding of the gums
  • Easy bruising
  • Excessive menstrual bleeding (menorrhagia)
  • Umbilical stump bleeding
  • Excessive bleeding following injury
  • Excessive bleeding following surgery
  • Excessive bleeding after giving birth
  • Prolonged bleeding time

Diagnosis

  • factor V assay (showing decreased activity)
  • activated partial thromboplastin time (aPTT) test (prolonged)
  • prothrombin time (PT) test (prolonged)
  • thrombin clotting time (TCT) test

Treatment

  • Fresh frozen plasma infusions (FFP). Depending upon availability, solvent-detergent FFP may contain a more reliable level of Factor V than standard FFP.
  • Fresh blood plasma infusions
  • In acute cases of severe bleeding, the addition of platelet concentrates may be helpful.
  • Patients with factor V deficiency can be given oral contraceptives to decrease menorrhagias, thereby improving anemia and decreasing transfusion needs.
  • Tooth extraction in a patient with factor V hereditary deficiency is safely performed with both supplementation of FFP and application of local hemostasis.

Daisy Jane Antipuesto RN MN

Currently a Nursing Local Board Examination Reviewer. Subjects handled are Pediatric, Obstetric and Psychiatric Nursing. Previous work experiences include: Clinical instructor/lecturer, clinical coordinator (Level II), caregiver instructor/lecturer, NC2 examination reviewer and staff/clinic nurse. Areas of specialization: Emergency room, Orthopedic Ward and Delivery Room. Also an IELTS passer.

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