Hemophilia A
Factor VIII deficiency; Classic hemophilia; Bleeding disorder - hemophilia AHemophilia A is a hereditary bleeding disorder caused by a lack of blood clotting factor VIII. Without enough factor VIII, the blood cannot clot properly to control bleeding.
Bleeding disorder
Bleeding disorders are a group of conditions in which there is a problem with the body's blood clotting process. These disorders can lead to heavy a...
Read Article Now Book Mark ArticleCauses
When you bleed, a series of reactions take place in the body that helps blood clots form. This process is called the coagulation cascade. It involves as many as 20 different special proteins called coagulation, or clotting, factors. You may have a higher chance of excess bleeding if one or more of these factors are missing or are not functioning like they should.
Factor VIII (eight) is one such coagulation factor. Hemophilia A is the result of the body not making enough factor VIII.
Hemophilia A is caused by an inherited X-linked recessive trait, with the variant gene located on the X chromosome. Females have two copies of the X chromosome. So if the factor VIII gene on one chromosome does not work, the gene on the other chromosome can do the job of making enough factor VIII.
X-linked recessive
Sex-linked diseases are passed down through families through one of the X or Y chromosomes. X and Y are sex chromosomes. Dominant inheritance occur...
Read Article Now Book Mark ArticleMales have only one X chromosome. If the factor VIII gene is missing on a boy's X chromosome, he will have hemophilia A. For this reason, most people with hemophilia A are male.
If a woman has a variant factor VIII gene, she is considered a carrier. This means the variant gene can be passed down to her children. Boys born to such women have a 50% chance of having hemophilia A. Their daughters have a 50% chance of being a carrier. All female children of men with hemophilia carry the variant gene whereas male children do not.
Risk factors for hemophilia A include:
- Family history of bleeding
- Being male
Symptoms
The severity of symptoms vary. Prolonged bleeding is the main symptom. It is often first seen when an infant is circumcised. Other bleeding problems usually show up when the infant starts crawling and walking.
Bleeding
Bleeding is the loss of blood. Bleeding may be:Inside the body (internal)Outside the body (external)Bleeding may occur:Inside the body when blood le...
Read Article Now Book Mark ArticleMild cases may go unnoticed until later in life. Symptoms may first occur after surgery or injury. Internal bleeding may occur anywhere.
Symptoms may include:
- Bleeding into joints with associated pain and swelling
Swelling
Swelling is the enlargement of organs, skin, or other body parts. It is caused by a buildup of fluid in the tissues. The extra fluid can lead to a ...
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Blood in the urine or stool
Blood in the urine
Blood in your urine is called hematuria. The amount may be very small and only detected with urine tests or under a microscope. In other cases, the...
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Bruising
Bruising
Bleeding into the skin can occur from broken blood vessels that form tiny red dots (called petechiae). Blood also can collect under the tissue in la...
Read Article Now Book Mark Article - Gastrointestinal tract and urinary tract bleeding
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Nosebleeds
Nosebleeds
A nosebleed is loss of blood from the tissue lining the nose. Bleeding most often occurs from one nostril only.
Read Article Now Book Mark Article - Prolonged bleeding from cuts, tooth extraction, and surgery
- Bleeding that starts without cause
Exams and Tests
If you are the first person in your family to have a suspected bleeding disorder, your health care provider will order a series of tests called a coagulation study. Once the specific variant has been identified, other people in your family will need tests to diagnose the disorder.
Tests to diagnose hemophilia A include:
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Prothrombin time (PT)
Prothrombin time
Prothrombin time (PT) is a blood test that measures the time it takes for the liquid portion (plasma) of your blood to clot. It measures the functio...
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Partial thromboplastin time (PTT)
Partial thromboplastin time
Partial thromboplastin time (PTT) is a blood test that looks at how long it takes for blood to clot. It can help tell if you have a bleeding problem...
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Serum factor VIII activity
Serum factor VIII
The factor VIII assay is a blood test to measure the activity of factor VIII. This is one of the proteins in the body that helps the blood clot....
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Treatment
Treatment includes replacing the missing clotting factor. You will receive factor VIII concentrates. How much you get depends on:
- Severity of bleeding
- Site of bleeding
- Your weight and height
Mild hemophilia may be treated with desmopressin (desamino-8-arginine vasopressin or DDAVP). This medicine helps the body release factor VIII that is stored within the lining of blood vessels.
To prevent a bleeding crisis, people with hemophilia and their families can be taught to give factor VIII concentrates at home at the first signs of bleeding. People with severe forms of the disease may need regular preventive treatment.
DDAVP or factor VIII concentrate may also be needed before having dental extractions or surgery.
You should get the hepatitis B vaccine. People with hemophilia are more likely to get hepatitis B because they may receive blood products.
Hepatitis B vaccine
All content below is taken in its entirety from the CDC Hepatitis B Vaccine Information Statement (VIS): www. cdc. gov/vaccines/hcp/vis/vis-statement...
Read Article Now Book Mark ArticleSome people with hemophilia A develop antibodies to factor VIII. These antibodies are called inhibitors. The inhibitors attack factor VIII so that it no longer works. In such cases, a man-made clotting factor called VIIa can be given.
Antibodies
An antibody is a protein produced by the body's immune system when it detects harmful substances, called antigens. Examples of antigens include micr...
Read Article Now Book Mark ArticleSupport Groups
You can ease the stress of illness by joining a hemophilia support group. Sharing with others who have common experiences and problems can help you not feel alone.
Hemophilia support group
The following organizations provide further information on hemophilia:Centers for Disease Control and Prevention -- www. cdc. gov/hemophilia/National...
Read Article Now Book Mark ArticleOutlook (Prognosis)
With treatment, most people with hemophilia A are able to lead a fairly normal life.
If you have hemophilia A, you should have regular checkups with a hematologist.
Possible Complications
Complications may include:
- Long-term joint problems, which may require a joint replacement
- Bleeding in the brain (intracerebral hemorrhage)
- Blood clots due to treatment
When to Contact a Medical Professional
Contact your provider if:
- Symptoms of a bleeding disorder develops
- A family member has been diagnosed with hemophilia A
- You have hemophilia A and you plan to have children; genetic counseling is available
Prevention
Genetic counseling may be recommended. Testing can identify women and girls who carry the hemophilia gene.
Genetic counseling
Genetics is the study of heredity, the process of a parent passing certain genes on to their children. A person's appearance, such as height, hair co...
Read Article Now Book Mark ArticleTesting can be done during pregnancy on a baby in the mother's womb.
References
Carcao M, Gomez K, Davide M, Pierce GF. Hemophilia A and B. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 8th ed. Philadelphia, PA: Elsevier; 2023:chap 134.
Ragni MV. Coagulation factor deficiencies. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 160.
Samelson-Jones BJ, Branchford BR, Flood VH. Hereditary clotting factor deficiencies (bleeding disorders). In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 525.
Review Date: 3/31/2024
Reviewed By: Todd Gersten, MD, Hematology/Oncology, Florida Cancer Specialists & Research Institute, Wellington, FL. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.