Acquired hemophilia is an autoimmune disorder in which the body’s immune system mistakes self-proteins as foreign and starts producing antibodies against them.
Commonly, the term hemophilia is used to denote the inherited bleeding disorder that affects mostly males from birth. This is called congenital or inherited hemophilia. But there is another condition called acquired hemophilia that shares few similarities with congenital hemophilia.
In acquired hemophilia, the immune system mistakes the blood clotting protein called factor VIII as foreign and starts to produce antibodies against it. As a result, factor VIII activity is inhibited, which leads to excessive bleeding.
In contrast to congenital hemophilia, acquired hemophilia can affect both males and females equally. The condition may develop at any age but usually affects much older people.
What causes acquired hemophilia?
In about half the cases, the cause for the immune overactivity against factor VIII is never established. In these cases, the condition is called idiopathic acquired hemophilia.
The immune system (composed of blood cells, lymph glands, and the spleen) protects the body from foreign molecules, bacteria, and viruses. Specific proteins called antibodies that bind to the foreign molecule or “invader” are synthesized, resulting in its clearance from the body.
In acquired hemophilia, the patient develops antibodies against blood-clotting factors, often against factor VIII. As a result, the antibody-bound factor is removed from the circulation, thereby impairing the clotting of the blood. This results in spontaneous bleeding episodes into the muscles, skin, and soft tissue, or prolonged bleeding after trauma or surgery.
In some people, acquired hemophilia may be associated with other illness such as rheumatoid arthritis, ulcerative colitis, asthma, psoriasis, and cancer. In rare cases, it may be triggered in response to drugs or by pregnancy.
How common is acquired hemophilia?
Acquired hemophilia is a very rare condition affecting approximately 1 in 1 million people. Most people have never heard of the condition. It is usually managed by a specialist at a hemophilia center in a hospital.
How is acquired hemophilia diagnosed?
In most cases, the first sign of the condition is extensive bruising on the body, particularly on the arms, legs, or trunk, which is distinct from injuries. The bruises may be very large, often extending the entire length of an arm or leg, and which fade with time.
Diagnosis should be considered if there is abnormal bleeding and a prolonged activated partial thromboplastin time (aPTT). Spontaneous bleeding may occur into the muscles, causing pain and temporary loss of movement. Acquired hemophilia is often characterized by prolonged bleeding after a surgical procedure or blood in the urine or stool. Specific symptoms may include nosebleeds (epistaxis), bruising throughout the body, solid swellings of congealed blood (hematomas), blood in the urine (hematuria), and gastrointestinal or urogenital bleeding.
A simple blood test is done to determine if the blood clotting system is working normally and the final diagnosis is made at a hemophilia center.
Is acquired hemophilia a serious condition?
Acquired hemophilia can be very serious if left undiagnosed. Once diagnosed, it can be successfully treated. Often, the antibody or inhibitor against factor VIII disappears without treatment, but the patient still needs regular check-ups and hospital care until then.
How is acquired hemophilia treated?
The first step in treating acquired hemophilia includes controlling immediate bleeding, which is followed by clearing the anti-factor VIII antibody from the body. Bleeding is controlled by injecting blood clotting factors directly into the patient’s bloodstream – most commonly a combination of clotting factors are used without the need for factor VIII. Such bypassing agents include recombinant activated factor VII (NovoSevenRT) or activated prothrombin complex concentrates (aPCC).
Once the diagnosis of acquired hemophilia is confirmed, other drugs are given to stop the production of anti-factor VIII antibody. This process is termed immune suppression. Immunosuppressive drugs are given for several months, and the blood is regularly tested for the presence of anti-factor VIII antibody. If the increase in antibody levels continues, a different combination of drugs is given.
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