What is factor XI deficiency?
Factor XI deficiency is an inherited bleeding disorder that is caused by a problem with factor XI. Because the body produces less factor XI than it should, or because the factor XI is not working properly, the clotting reaction is blocked prematurely and the blood clot does not form.
Factor XI deficiency is also called haemophilia C. It differs from haemophilia A or B in that there is no bleeding into joints and muscles. Factor XI deficiency is the most common of the rare bleeding disorders and the second most common bleeding disorder affecting women (after von Willebrand disease).
Some people have inherited factor XI deficiency when only one parent carries the gene. The disorder is most common among Ashkenazi Jews, that is, Jews of Eastern European ancestry.
Most people with factor XI deficiency will have little or no symptoms at all. The relationship between the amount of factor XI in a person's blood and the severity of his/her symptoms is unclear; people with only a mild deficiency in factor XI can have serious bleeding episodes. Symptoms of factor XI deficiency vary widely, even among family members, which can make it difficult to diagnose.
- nosebleeds (epistaxis)
- easy bruising
- heavy or prolonged menstrual bleeding (menorrhagia)
- abnormal bleeding during or after surgery, injury, or childbirth
Other reported symptoms
- bleeding in the gut (gastrointestinal hemorrhage)
- bleeding in the mouth, particularly after dental surgery or tooth extraction
- blood in the urine (hematuria)
Factor XI deficiency is diagnosed by a variety of blood tests that should be performed by a specialist at a haemophilia/bleeding disorders treatment centre.
There are several treatments available to help control bleeding in people with factor XI deficiency.
- Factor XI concentrate
- Antifibrinolytic drugs
- Fibrin glue
- Fresh frozen plasma (FFP)
Excessive menstrual bleeding in women with factor XI deficiency may be controlled with hormonal contraceptives (birth control pills), intra-uterine device (IUDs), or antifibrinolytic drugs.