Diagnosis of Hemophilia A

Diagnostic tests can differentiate between hereditary and acquired forms

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Hemophilia A is a condition where the clotting ability of the blood is impaired. It is diagnosed based on a factor VIII level that is measured in the blood, and often with a blood test that can identify the genetic abnormality.

You or your child may have diagnostic testing to identify this condition for evaluation of symptoms or due to a family history of the condition. Additionally, you might get tested for family planning if you think you are a carrier of the condition. 

If you already have been diagnosed with Hemophilia A, you may also need diagnostic tests to assess complications of the condition. This can start with your own self-checks at home, but you may need more specific medical testing in some situations. 

Blood tests are used to diagnose hemophilia A

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Self-Checks/At-Home Testing 

Living with hemophilia A means that you need to recognize bleeding problems. In many instances, bleeding from a cut or a wound will be visibly apparent. 

You might not feel pain associated with bleeding, so you should check your skin whenever you have any injuries. You also need to examine your skin after shaving, a manicure or pedicure that involves clipping, or professional hair-removal waxing.

After any medical procedure, it’s important that you are attentive to the area that’s being treated so that you can quickly identify bleeding. This can include checking your gums after having dental work or checking your skin after getting an injection or having your blood drawn. 

Bruising can also be a problem. Examine your skin after activities like getting a massage, participating in sports or exercise, physical work, and lifting objects. 

Additionally, internal wounds can cause bleeding that can manifest in a variety of ways. 

Things to look for include:

Excessive bleeding may also cause fatigue or dizziness. 

Monitoring a Child

If you are a parent of a child who has hemophilia A, you will need to monitor these issues so you can identify bleeding problems if they occur. Eventually, you also will need to teach your child how to recognize them.

Physical Examination 

If you have an initial evaluation for symptoms of hemophilia A, your healthcare professional will examine you for signs of bleeding or bruising and for associated symptoms.

For example, liver disease can also lead to bleeding due to the impairment of its ability to make proteins essential for clotting. It also causes jaundice (yellow skin and eyes), so your provider would do a comprehensive physical examination to consider a range of possible causes of your bleeding.

If you have already been diagnosed with hemophilia A, your routine physical examinations and any that you have for worsening symptoms would include checks of your gums, throat, and nasal passages. Your provider would also check skin for wounds or bruises and check joints for signs of swelling. 

Labs and Tests

Diagnosis of hemophilia A relies on blood tests. There are several types of tests, and they can distinguish between congenital hemophilia A (which is present from birth) and acquired hemophilia A (which may develop during adulthood).

Blood tests that can diagnose this condition include:

  • Prothrombin time (PT) and partial thromboplastin time (PTT): These tests assess how long it takes for your blood to clot. With hemophilia A, PTT is prolonged and PT is normal.
  • Factor VIII: This clotting protein is reduced in hemophilia A. The severity of hemophilia A is determined by the amount of factor VIII in the blood.
Severity of Hemophilia A
Mild  Factor VIII level of 6%-30%
Moderate  Factor VIII level of 1%-5%
Severe  Factor VIII level less than 1%
  • Autoantibodies against factor VIII: This is present with acquired hemophilia A.
  • Genetic test: A mutation in the F8 gene on the X chromosome is present in congenital hemophilia A.
  • Activated PTT (aPTT) mixing tests: A sample of blood is mixed with normal blood. With congenital hemophilia A, the aPTT is normal because the healthy blood contains factor VIII. With acquired hemophilia A, the aPTT is abnormal because the antibodies against factor VIII prevent this protein from having normal blood clotting activity.
  • Inflammatory markers: Acquired hemophilia A is associated with autoimmune conditions. Your doctor may check your blood tests to see if you could have an undiagnosed autoimmune disorder, such as lupus.

Additionally, you may have a complete blood count (CBC) to check for anemia if there is a concern that you have been losing red blood cells due to bleeding.


Imaging tests are not part of the standard diagnosis of hemophilia A. However, you might need an imaging test to assess symptoms of internal bleeding, such as joint swelling (which can be caused by bleeding in the joints) or headaches (which can be caused by bleeding in the brain).

Differential Diagnosis 

Several other conditions can cause bleeding. During your evaluation, your doctor might consider these other conditions, especially if you begin to have symptoms without a family history of hemophilia A.

Liver disease, von Willebrand disease, hemophilia B, and platelet disorders can cause bleeding problems. Diagnostic blood tests will differentiate between hemophilia A and other bleeding disorders.


There are several different times in your life when you might need testing for hemophilia A. Hemophilia A is diagnosed based on blood tests that measure factor VIII. You can also have a genetic test to identify the gene mutation that’s associated with the disease.

You might be tested if you have symptoms or a family history of the condition. You might also be tested before or during pregnancy if you or the other genetic parent has hemophilia A or could be a carrier.

People who have been diagnosed with hemophilia A may also need diagnostic testing to identify bleeding complications. 

A Word From Verywell

Recurrent and frequent bleeding is dangerous. If you have experienced bleeding issues, it’s important that you see a doctor to learn why this is happening.

If you have hemophilia A or a family history of the condition, it’s important to be attentive to bleeding complications—a timely diagnosis of complications is vital to treatment.

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5 Sources
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