Prothrombin deficiency
Key points
- Factor II deficiency is a disorder of blood clotting (coagulation) resulting from a deficiency of prothrombin.
- Normal blood coagulation is a complex process involving as many as 20 different plasma proteins, which are known as blood coagulation factors.
- Treatment Loss of blood can be controlled by infusions of fresh or frozen plasma or concentrates of clotting factors.
- The stress of illness can often be helped by joining a support group where members share common experiences and problems.
Alternative names
Hypoprothrombinemia; Factor II deficiency
Definition
Factor II deficiency is a disorder of blood clotting (coagulation) resulting from a deficiency of prothrombin.
Causes, incidence, and risk factors
Normal blood coagulation is a complex process involving as many as 20 different plasma proteins, which are known as blood coagulation factors. A series of complex chemical reactions using these factors takes place very rapidly to form an insoluble protein called fibrin that stops bleeding. When certain coagulation factors are deficient or missing, the chain reaction does not take place normally. In this disorder, bleeding ranges from mild to severe.
A congenital factor II deficiency is a very rare inherited disorder that results in deficient blood clotting. It is inherited as an autosomal recessive trait (both parents are carriers). A family history of a bleeding disorder is a risk factor.
Acquired factor II deficiency is common and results from vitamin K deficiency, severe liver disease, and therapeutic use of anticoagulant drugs. Risk factors for vitamin K deficiency are prolonged use of antibiotics, bile duct obstruction, and intestinal malabsorption (inadequate absorption of nutrients from the intestinal tract) disorders. Some newborns are born with vitamin K deficiency.
Symptoms
- Umbilical cord bleeding at birth
- Nose bleeds
- Abnormal menstrual bleeding
- Abnormal bleeding after delivery
- Bleeding after trauma
- Bleeding after surgery
- Bruising
Signs and tests
- Prolonged prothrombin time
- Prolonged partial thromboplastin time
- Factor II assay showing decreased activity
Treatment
Loss of blood can be controlled by infusions of fresh or frozen plasma or concentrates of clotting factors. If the disorder is caused by vitamin K deficiency, then vitamin K is prescribed. Diagnosis of a bleeding disorder is important so that precautionary measures can be taken if surgery is needed or anticipated.
Support Groups
The stress of illness can often be helped by joining a support group where members share common experiences and problems. See hemophilia - resources.
Written and revised by
David Cohen, M.D.
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