Factor VII deficiency is a blood clotting disorder that causes excessive or prolonged bleeding after an injury or surgery. With Factor VII deficiency, your body either doesn’t produce enough factor VII, or something is interfering with your factor VII, often another medical condition.
Factor VII is a protein produced in the liver that plays an important role in helping your blood to clot. It is one of about 20 clotting factors involved in the complex process of blood clotting. To understand Factor VII deficiency, it helps to understand the role factor VII plays in normal blood clotting.
The normal blood clotting process occurs in four stages:
When a blood vessel is cut, the damaged blood vessel immediately constricts to slow blood loss. Then, the injured blood vessel releases a protein called tissue factor into the blood stream. The release of tissue factor acts like an SOS call, signaling blood platelets and other clotting factors to report to the scene of the injury.
2. Formation of a platelet plug.
Blood platelets are the first to arrive at the injury site. They attach themselves to the damaged tissue, and to each other, forming a temporary, soft plug in the wound. This process is known as primary hemostasis.
3. Formation of a fibrin plug.
Once the temporary plug is in place, the blood clotting factors go through a complex chain reaction to release fibrin, a tough, stringy protein. Fibrin wraps itself in and around the soft clot until it becomes a tough, insoluble fibrin clot. This new clot seals the broken blood vessel, and creates a protective covering for new tissue growth.
4. Wound healing and destruction of the fibrin plug.
After a few days, the fibrin clot starts to shrink, pulling the edges of the wound together to help new tissue grow over the wound. As the tissue is rebuilt, the fibrin clot dissolves and is absorbed.
If factor VII does not function properly, or there is too little of it, the stronger fibrin clot cannot form properly.
Factor VII deficiency may be either inherited or acquired. The inherited version is quite rare. Fewer than 200 documented cases have been reported. Both of your parents must carry the gene in order for you to be affected.
Acquired Factor VII deficiency, in contrast, occurs after birth. It can occur as a result of medications or diseases that interfere with your factor VII. Drugs that can impair or reduce factor VII function include:
- blood thinners such as warfarin
- some cancer drugs, such as interleukin-2 therapy
- antithymocyte globulin therapy used to treat aplastic anemia
Diseases and medical conditions that can interfere with factor VII include:
- liver disease
- aplastic anemia
- vitamin K deficiency
Symptoms vary from mild to severe, depending on your levels of usable factor VII. Mild symptoms might include:
- bruising and soft tissue bleeding
- longer bleeding time from wounds or dental extractions
- bleeding in joints
- bleeding gums
- heavy menstrual periods
In more severe cases, symptoms can include:
Diagnosis is based on your medical history, any family history of bleeding problems, and lab tests.
Lab tests for factor VII deficiency include:
- factor assays to identify missing or poorly performing factors
- factor VII assay to measure how much factor VII you have, and how well it works
- prothrombin time (PT) to measure the functioning of factors I, II, V, VII, and X
- partial prothrombin time (PTT) to measure the functioning of factors VIII, IX, XI, XII, and von Willebrand factors
- inhibitor tests to determine if your immune system is attacking your clotting factors
Treatment of Factor VII deficiency focuses on (1) controlling bleeding, (2) resolving underlying conditions, and (3) precautionary treatment before surgery or dental procedures.
During bleeding episodes, you may be given infusions of blood clotting factors to boost your clotting ability. Clotting agents commonly used include human prothrombin complex, cryoprecipitate, fresh frozen plasma, or recombinant human factor VIIa (NovoSeven).
Treatment of Underlying Conditions
Once bleeding is under control, conditions that impair factor VII production or functioning, such as medications or diseases, must be addressed.
Precautionary Treatment Before Surgery
If you are planning surgery, your doctor may prescribe drugs to minimize your risk of excessive bleeding. Desmopressin (DDAVP) nasal spray is often prescribed to release all available stores of factor VII before minor surgery. For more serious surgeries, your doctor may prescribe infusions of clotting factor.
If you have the acquired form of factor VII deficiency, it is probably caused by either medications, or an underlying condition. Your long-term outlook depends on fixing the underlying problems. If you have the more severe inherited form of factor VII deficiency, you will need to work closely with your doctor and your local hemophilia center to manage bleeding risks.