What Is Acquired Haemophilia?

  • Sara Nakanishi   Master’s of Science - Genes, Drugs, and Stem Cells - Novel    Therapies, Imperial College London
  • Ellie Kerrod BSc Neuroscience - The University of Manchester, England
  • Richard Stephens Doctor of Philosophy(PhD), St George's, University of London


Definition of acquired haemophilia

Acquired Haemophilia is a rare autoimmune bleeding disorder. In acquired haemophilia, your body creates molecules called autoantibodies to attack certain clotting factors in your blood. Without these factors, your body cannot properly clot (coagulate) your blood, making you bleed uncontrollably. This can be deadly if not treated quickly.1

Antibodies are usually a good immune response. Your body will create antibodies called IgA and IgM to attack foreign viruses and bacteria in your body to fight off illnesses such as COVID-19 or the common cold. This is crucial for your body to recover. However, in the case of an autoimmune disorder, your body will mistake some of your own body’s cells as foreign and create specific antibodies to attack them, also known as autoantibodies. Some examples of autoimmune disorders include multiple sclerosis, rheumatoid arthritis, and Crohn’s disease.1

There are two main types of acquired haemophilia: A and B. The type depends on which clotting factor is affected. 

Acquired haemophilia A (AHA)

Haemophilia A is when you don’t have enough clotting factor 8 (VIII) in your blood. This is the most common type of haemophilia in people. Acquired haemophilia is reported to occur in 1.5 cases per 1 million people each year. A majority of the cases occur in those older than 65 and of this group, half have another autoimmune disorder.1

Acquired haemophilia B (AHB)

Haemophilia B is when you don’t have enough clotting factor 9 (IX) in your blood. This is extremely rare.1

What are clotting factors?

Imagine when you get a paper cut or scrap your knee, you initially have blood flowing but after a few minutes, the blood stops and your cut dries and eventually scabs over and heals. This is an example of your blood clotting.1 Your body has 12 clotting factors that work together to clot your blood. Clotting is when your blood turns into a thicker gel-like substance that acts as a barrier when you have damage to your blood vessels to stop the blood from leaking out.1

Causes and risk factors

Underlying conditions leading to acquired haemophilia

In approximately 50% of diagnosed cases of acquired haemophilia, there is no recognised cause. In the other 50% of cases, there is an identified risk or cause of the disorder. Many underlying causes can lead to acquired haemophilia. Some include:2

Other immune disorders

In approximately 17-18% of the cases with an identified cause, the patient already has another autoimmune disorder. This could include rheumatoid arthritis, systemic lupus erythematosus, multiple sclerosis, or connective tissue diseases to name a few examples.2

Obstetrical causes

In approximately 8% of the causes, acquired haemophilia is diagnosed in the immediate time after one has given birth, also referred to as the post-partum period. For up to 12 months after giving birth, abnormal bleeding should be checked out as it might be due to acquired haemophilia A.2


Some cancers can result in acquired haemophilia. Solid tumours, precancerous states, and non-Hodgkins lymphoma can cause this as well as blood cancers such as chronic lymphocytic leukaemia.2

Some conditions such as psoriasis or pemphigus can lead to acquired haemophilia.2


Antibiotics, psychiatric and immunomodulatory drugs such as interferon have been associated with AHA.4

Infectious diseases

Including acute hepatitis B and C infections, and other infectious illnesses.5


This can be a result of rejection from a transplant such as graft versus host disease where the body is attacking the transplant.2


Some cases of asthma and chronic obstructive pulmonary disease(COPD) have been reported as a cause or risk of acquired haemophilia.2


Acquired haemophilia is specific to those who bleed with varying severity without a previous personal or family history of haemophilia. The National Organization for Rare Disease reports that one-third of patients do not require therapy to control the bleeding, however, more than one-third of the patients suffer more than one bleeding episode. 

The bleeding episodes can present in multiple places: 

Commonly, the bleeding occurs without an immediately obvious cause, such as a trauma or cut. Because of the lack of clotting, these episodes of bleeding can become severe depending on location and amount and can become life-threatening fast.

Additional symptoms may include:

  • Bleeding gums
  • Pain and stiffness in the joints (due to internal bleeding)


Laboratory tests used to confirm acquired haemophilia

To diagnose acquired haemophilia, laboratory tests are needed to measure how the clotting system is functioning.3 Prolonged clotting factor expression, like the factor being “always on”, can tell the doctor if something is missing or wrong with the cycle. The doctors will run what is called a haemostatic assay. In this, they will be able to measure:3

These measures are important for understanding how long it takes for your blood to coagulate. In patients with acquired haemophilia, the assay should report normal PT and prolonged aPTT levels. After this assay, they will run other tests to rule out other causes of prolonged aPTT, such as the presence of Lupus or a deficiency of clotting factors 7 (VII) and/or 11 (XI).3

Your doctor will most likely run an antibody titre test. This is used to detect the strength of the immune response against your own body’s tissues. For this test, your doctor will draw your blood and can run many tests on it. One such test is called an enzyme-linked immunoassay (ELISA). This laboratory test is used to identify the presence of a certain antibody. The sample is prepared and if the test turns a colour, typically purple, this is a positive indication that the antibody is present. This is done to identify the autoantibodies that deactivate the clotting factors.

It is important to properly diagnose acquired haemophilia. Improper diagnosis can cause adverse effects from improper treatment. Acquired haemophilia can commonly be mistaken for congenital haemophilia or antiphospholipid syndrome.3

Treatment and management

Because acquired haemophilia is rare, treatment is personalized to the patient. Not enough studies have been conducted to create a “gold standard” treatment plan. It is important to have a detailed discussion with your physician and other medical professionals on the best course of treatment. Factors that are included in the direction of treatment include:1

  • Past medical history including previous disorders and response to certain medications
  • Current symptoms present
  • Age and overall health
  • Personal preference for treatment

There have been reported cases of remission during the post-partum period, allergic reactions to drugs, and those with low levels of inhibitors during the titre test.

There are three goals for treatment: stop the bleeding, prevent future bleeding, and treat the underlying cause, if there is one.

Haemostatic management is for patients who experience severe bleeding and decreased haemoglobin, a protein responsible for delivering oxygen through the blood. This is done by administering haemostatic agents to bypass the missing clotting factor that has been taken away by the autoantibodies. This can be done with certain plasma derivatives or complexes, such as Cryoprecipitated Antihaemophilic Factor (Cryo), that help clot the blood.2

Inhibitor eradication is an immunosuppressive (IST) therapy using glucocorticoids and other agents. This treatment's goal is to eradicate, or destroy, the autoantibodies to resolve the risk of life-threatening bleeds. Some of the medication includes prednisone alone or with cyclophosphamide, as the use of both is correlated with better patient outcomes. Success is dependent on the results of the antibody titre and measured levels of the affected clotting factor. While the goal is the eradicate the autoantibody, there are still reports of relapses, so it is important to follow up with your medical team when necessary.2

What is the fatality rate?

Without diagnosis and proper treatment, acquired haemophilia has a high morbidity and mortality rate. Those with this disease can have catastrophic uncontrollable bleeding. For acquired haemophilia A, the mortality rate is between 8-22%. In cases where acquired haemophilia A is present in the post-partum period, the recovery rate is 97%.1


Acquired haemophilia is a rare autoimmune disorder that causes uncontrollable bleeding. Without proper diagnosis and treatment, this disorder can be deadly. There are 2 main types of acquired haemophilia: A and B. A is the most common type, with an antibody targeting clotting factor 8, and B, the rare form, targeting clotting factor 9. 

The main symptom of acquired haemophilia is bleeding in varying severity and locations without an underlying cause or trauma that induces the bleeding. Acquired haemophilia can be diagnosed with several laboratory tests that will help the doctor understand what is wrong with the blood and identify the presence of the autoantibodies. 

Only occurring approximately once in every million people per year, this disorder has no one-size-fits-all treatment and is mainly based on symptoms, progression, health, and personal medical history. Treatment is focused on stopping and preventing major bleeding and eradicating the autoantibodies from the system.


  1. Sridharan M, Pruthi RK. Autoimmune (Acquired) Hemophilia: Updates in Diagnosis and Therapy. The Hematologist [Internet]. 2022 Feb 25 [cited 2023 Aug 8];19(2). Available from: https://doi.org/10.1182/hem.V19.2.2022214
  2. Haider MZ, Anwer F. Acquired Hemophilia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Aug 10]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK560494/
  3. Müller J, Miesbach W, Prüller F, Siegemund T, Scholz U, Sachs UJ. An Update on Laboratory Diagnostics in Haemophilia A and B. Hamostaseologie 2022;42:248–60. https://doi.org/10.1055/a-1665-6232.
  4. Franchini M, Capra F, Nicolini N, Veneri D, Manzato F, Baudo F, et al. Drug-induced anti-factor VIII antibodies: a systematic review. Med Sci Monit. 2007; 13(4):RA55-61.  Available from: https://medscimonit.com/abstract/index/idArt/481687.
  5. Haider MZ, Anwer F. Acquired Hemophilia. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 [cited 2023 Nov 25]. Available from: http://www.ncbi.nlm.nih.gov/books/NBK560494/.
This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

Get our health newsletter

Get daily health and wellness advice from our medical team.
Your privacy is important to us. Any information you provide to this website may be placed by us on our servers. If you do not agree do not provide the information.

Sara Nakanishi

Master’s of Science - Genes, Drugs, and Stem Cells - Novel Therapies, Imperial College London

Bachelor of Science - Biochemistry/Chemistry, University of California San Diego

Hello! My name is Sara and I have a diverse background in science, particularly in biochemistry and therapeutics. I am extremely passionate about heart health and mental illness. My goal is to break down complex scientific topics to share with those with non-scientific backgrounds so they can be well-informed about their conditions and ways to live a balanced life. I believe that education and awareness are key to leading a healthy lifestyle and I hope to inspire others through my writing.

Leave a Reply

Your email address will not be published. Required fields are marked *

my.klarity.health presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
Klarity / Managed Self Ltd
Alum House
5 Alum Chine Road
Westbourne Bournemouth BH4 8DT
VAT Number: 362 5758 74
Company Number: 10696687

Phone Number:

 +44 20 3239 9818