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Hemophilia A vs. B

Posted on September 28, 2022
Medically reviewed by
Todd Gersten, M.D.
Article written by
Jane Chung, PharmD, RPh

Hemophilia A and hemophilia B are two types of hemophilia that produce similar symptoms and are diagnosed with the same medical tests. Although both are rare bleeding disorders, hemophilia A is much more common than hemophilia B. The main difference between the two conditions is which clotting factor (coagulation factor) is missing or ineffective. Insufficient clotting factors put people with hemophilia A or B at risk of uncontrolled bleeding.

Understanding the type of hemophilia is important for getting proper treatment. Hemophilia A and B are both treated by replacing the body’s missing or low clotting factor, but there are some differences in the medications and treatment options for each.

What Is Hemophilia A?

Hemophilia A is a blood clotting disorder that occurs when the body doesn’t have sufficient amounts of blood clotting factor 8, due to mutations (changes) to the factor 8 gene. Also called classic hemophilia, it is often genetically inherited (passed down through genes) from parents, but about 30 percent of people with the condition have no known family history.

What Is Hemophilia B?

Hemophilia B is also called Christmas disease because it was named after Stephen Christmas, who, in 1952, became the first person diagnosed with the condition. It occurs when the body doesn’t have enough levels of blood clotting factor 9. It is caused by mutations to the factor 9 gene. Hemophilia B is also a genetically inherited condition, but as with hemophilia A, about 30 percent of people with the condition don’t have a family history of it.

How Common Are Hemophilia A and B?

Hemophilia A is the most common type, affecting about 80 percent to 85 percent of people with hemophilia. Per NORD (the National Organization for Rare Disorders), about 1 in every 5,000 to 10,000 males is affected. This condition affects people of all races and ethnicities equally. According to the Centers for Disease Control and Prevention (CDC), hemophilia A is about four times as common as hemophilia B.

Hemophilia B is the second most common type of hemophilia but accounts for only about 15 percent to 20 percent of cases of hemophilia. Approximately 1 in every 25,000 to 30,000 males is affected. About 10 percent to 25 percent of carrier females (people with one normal X chromosome and one chromosome with the mutated gene for the condition) may develop mild symptoms. In rare instances, moderate to severe symptoms may occur. As with hemophilia A, hemophilia B equally affects all races and ethnicities.

How Do the Symptoms of Hemophilia A and B Compare?

The symptoms of hemophilia A and hemophilia B are similar. Because hemophilia affects the body’s ability to clot blood, the main symptoms involve uncontrolled bleeding in different parts of the body. Symptoms are usually categorized by the severity of the condition, which ranges from mild to moderate to severe. Severity varies from person to person.

Mild Hemophilia A or B

For hemophilia A, people who have 5 percent to 40 percent of normal factor 8 levels are considered to have mild hemophilia A. Mild hemophilia B is defined as having 6 percent to 49 percent of clotting factor 9 levels in the blood.

Symptoms may include gum or nose bleeding, as well as bruising. Prolonged and/or excessive bleeding may occur after serious surgery, trauma, or injury. People with mild hemophilia may experience heavy menstrual periods and possible hemorrhaging (bleeding from broken blood vessels) after childbirth.

A member of MyHemophiliaTeam said, “I have factor 8 levels in the low 40 percent range and tend to bruise easily.”

Moderate Hemophilia A or B

Moderate hemophilia A and hemophilia B occur when 1 percent to 5 percent of normal factor 8 and factor 9 levels, respectively, are present in the blood.

In moderate hemophilia A or B, people may experience bleeding for a long time after surgery, dental procedures, or trauma or injuries. Bruising will also occur easily. People may also experience episodes of bleeding that happen without an obvious cause.

Severe Hemophilia A or B

In severe hemophilia A, a person has less than 1 percent of normal factor 8 levels. Similarly, a person with severe hemophilia B has less than 1 percent of clotting factor 9 levels.

At this level, spontaneous bleeding can occur with no apparent cause. Bleeding can happen in the deep muscles or joints (known as hemarthrosis). This can lead to pain, swelling, and limited movement in the affected joint(s). If the bleeding is not treated quickly, it can cause longer-term arthritis (joint inflammation).

One MyHemophiliaTeam member shared, “I am 62 with severe hemophilia A, and I am currently experiencing chronic pain in both elbows, both ankles, and both knees.”

In addition to affecting the muscles and joints, spontaneous bleeding may occur in any organ, including:

  • The kidneys — Causes blood in the urine
  • The digestive tract — Causes blood in the stool
  • The brain (intracranial) — Causes headaches, vomiting, and seizures

If left untreated, spontaneous bleeding can be life-threatening.

How Are Hemophilia A and B Diagnosed?

Hemophilia A and B are diagnosed in similar ways. Making a diagnosis of hemophilia A or B is based on symptoms, family history, and results of blood tests, such as complete blood counts (CBCs), coagulation tests, and factor assays.

Complete Blood Count

A CBC test measures the amounts of hemoglobin (the part of red blood cells that carries oxygen), red blood cells, white blood cells, and platelets in the blood. People with hemophilia usually have normal CBC test results, although heavy bleeding can lower hemoglobin and red blood cell counts.

Coagulation Tests

Coagulation tests measure how long it takes for blood to clot. They include the activated partial thromboplastin time (aPTT) test and the prothrombin time (PT) test. In people with hemophilia A, the PT test result is usually normal. The aPTT test result is longer when the factor 8 level is less than 30 percent of normal.

Factor Assays

Factor assays are also known as clotting factor tests. These tests show the type of hemophilia as well as the level of severity. After an abnormal aPTT test result, factor assays are used to confirm the diagnosis of the type of hemophilia. The assay would show which clotting factor is deficient — a factor 8 deficiency indicates hemophilia A, and a factor 9 deficiency indicates hemophilia B.

Even if an aPTT test result is normal, factor assays should be performed in people suspected of having hemophilia A or B. This is because aPTT tests are prone to false-negative results, especially in those with hemophilia.

What Are the Treatments for Hemophilia A and B?

There is no cure for hemophilia A or B, but both conditions can be treated effectively. Hemophilia A and B are treated by replacing the clotting factors that are lacking, either through a clotting factor product that’s produced in a lab or through one derived from human blood and plasma donations. This type of treatment is called factor replacement therapy.

Factor replacement therapy can be given as needed, after bleeding episodes, in people with mild to moderate hemophilia A or B. This is called “on-demand” therapy.

“I have factor 9 hemophilia,” shared one member. “I only take factors on demand, so I don’t run out quickly.”

Severe cases of hemophilia A and B are treated through prophylaxis. This means that people receive clotting factors regularly to prevent bleeding.

Mild cases of hemophilia A can also be treated with desmopressin (DDAVP), which is a human-made version of the vasopressin hormone. DDAVP works by increasing factor 8 levels in the blood. Antifibrinolytics can also be used for mild hemophilia A. These are drugs that slow the breakdown of clotting factors in the blood.

Recombinant Clotting Factors

Factor replacement therapy can be done with recombinant clotting factors, which are clotting factors produced in a laboratory. Recombinant factors do not contain any parts of human blood.

Recombinant products are usually the preferred treatment as compared to products derived from real human blood because they do not contain human proteins or the risk of viruses. Scientific advancements have greatly reduced the risk of viral infection — such as hepatitis or HIV — from human blood donations, but there is still a very small risk of contracting a virus through these donations.

Several recombinant factor 8 products have been approved by the U.S. Food and Drug Administration (FDA) for hemophilia A. These are available under brand names like:

    Recommended recombinant factor 9 treatments for people with hemophilia B include:

    Human Plasma-Derived Preparations

    Factor 8 can be obtained from frozen plasma (the liquid part of the blood), which people donate.

    Examples of brand-name hemophilia A plasma products include:

    Factor 9 can be derived from frozen plasma and is called plasma-derived factor 9 concentrate. This product comes from human donations of blood or plasma and is concentrated to varying degrees to filter out other clotting factors and inactivate any viruses present in the blood. High-purity plasma-derived factor concentrates are free of other clotting factors and have all viruses inactivated.

    Examples of this product for hemophilia B include AlphaNine SD and Mononine.

    Fresh Frozen Plasma

    Fresh frozen plasma (FFP) is another option for replacing clotting factors, but it is only used for factor 9 deficiency when a factor 9 concentrate is not available. It’s made with human blood and contains all clotting factors typically present in the blood. FFP is not very effective at raising the levels of factor 9, so it isn’t a preferred treatment.

    Regardless of the type of hemophilia, the CDC recommends management steps like treating bleeds early and getting a comprehensive checkup from your hemophilia care doctor regularly.

    What’s the Outlook for People With Hemophilia A or B?

    People with hemophilia A and hemophilia B will have normal life spans. People with hemophilia should be educated and informed about their condition and receive the appropriate treatments.

    Communicate With Your Health Care Provider

    Talk to your doctor to learn more about your type of hemophilia. Ask your doctor to explain how your type may shape your journey as a person with hemophilia.

    Talk With Others Who Understand

    MyHemophiliaTeam is the social network for people with hemophilia and their loved ones. On MyHemophiliaTeam, more than 6,000 members come together to ask questions, give advice, and share their stories with others who understand life with hemophilia.

    Are you living with hemophilia? Which type do you have, and how do you manage it? Share your experience in the comments below, or start a conversation by posting on your Activities page.

      All updates must be accompanied by text or a picture.
      Todd Gersten, M.D. is a hematologist-oncologist at the Florida Cancer Specialists & Research Institute in Wellington, Florida. Review provided by VeriMed Healthcare Network. Learn more about him here.
      Jane Chung, PharmD, RPh earned a Bachelor of Science in Pharmacy Studies and a Doctor of Pharmacy from Northeastern University in Boston, MA. Learn more about her here.

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