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ACQUIRED HEMOPHILIA

If you have acquired hemophilia, your body forms antibodies that attack one of the clotting factors needed to form a sufficient blood clot. Most commonly, antibodies are formed against clotting factor聽 VIII (FVIII), but they can form against any of the clotting factors. Similar to traditional (congenital)聽 hemophilia with an inhibitor, when antibodies form against a factor protein, the protein is destroyed.聽 This leads to a deficiency in that protein, which leads to the inability to effectively stop bleeding. An estimated 0.2-1.0 people per million are diagnosed with acquired hemophilia, making it even more rare than congenital hemophilia.

CAUSES

Acquired hemophilia is not inherited. It is an autoimmune disorder, which means that the body begins to recognize its own factor protein as foreign and attacks it. In about half of all cases, there is an underlying disease process or event that leads to this. In the other half, there is no known cause. Other autoimmune disorders, pregnancy (post-partum), cancer, and certain drug reactions have been linked to the development of acquired hemophilia, and there may be a link to some infectious diseases,聽 dermatologic disorders, respiratory disorders, and diabetes.

WHO DOES IT AFFECT

Acquired hemophilia is more common in the elderly population, with the exception of pregnancy. The median age of diagnosis is 64-78 years of age, and because it is not an inherited condition, it affects men and women equally. While there have been some cases of acquired hemophilia in children, it is very rare.

SYMPTOMS

The most common types of bleeding in acquired hemophilia are subcutaneous, gastrointestinal (GI),聽 muscular, genitourinary (GU), and retroperitoneal. It is important to note that, unlike congenital hemophilia, joint bleeding is rare in acquired hemophilia. Intracranial hemorrhage is also rare but can be fatal.

DIAGNOSIS

Diagnosis of acquired hemophilia can be challenging and easily be delayed due to how rare the disease is, lack of personal or family history of bleeding, variation in symptoms on presentation and challenging lab workup. Lab tests that are diagnostic for acquired hemophilia are a prolonged activated partial thromboplastin time (aPTT), normal prothrombin time (PT), low factor level聽 (typically FVIII), aPTT mixing study that does not correct, and the presence of an inhibitor to one of the factor proteins. Tests to rule out other causes of inhibitor development must also be performed聽 (Lupus anticoagulation and heparin therapy).

TREATMENT

There are three main goals in treating acquired hemophilia:

  1. Control active bleeding– Active bleeding is treated using either an activated prothrombin complex concentrate (such as FEIBA, which contains activated factors VII, IX, and X) or

recombinant activated factor VII (NovoSeven). Both are given intravenously and聽duration/frequency depends on the product and response to treatment.

  1. Eradicate the inhibitor 鈥 Because acquired hemophilia is an autoimmune disorder, getting rid of the inhibitor involves suppressing the immune system so that it stops creating inhibitory antibodies to the factor protein. Treatment may include steroids (such as prednisone),聽 Rituximab, Mycophenolate and Cyclosporin.
  2. Treat any identified underlying cause– Examples of this would be stopping any medication thought to have contributed to its development or treating the underlying malignancy or autoimmune disorder.

The risks associated with treatment must also be taken into consideration, particularly since many people with acquired hemophilia have other co-morbidities which complicate their treatment picture. Risks such as infection due to immune suppression and clot formation must be balanced with the risk of possible injury or death related to severe bleeding.

PROGNOSIS

While acquired hemophilia is a very serious and potentially fatal disease, complete remission is achieved in almost three-quarters of people who are treated. There have also been reports of spontaneous remission post-partum and after specific medications contributing to the development of acquired hemophilia were stopped. Overall prognosis in these situations is good.

Unfortunately, relapse does occur in about 20% of people within the first 2-14 months of treatment and inhibitor-related mortality rate is around 11%. This underlies the need for efficient diagnosis and treatment.

REFERENCES

JOURNAL ARTICLES

Haider MZ, Anwer F. Acquired Hemophilia. 2021 Oct 1. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan鈥. PMID: 32809329.

Huth-Kunhe A, Baudo F, Collins P, et al. International recommendations on the diagnosis and treatment of patients with acquired hemophilia A. Haematologica. 2009;94:566-575. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2663620/?tool=pubmed

Kruse-Jarres R, Kempton CL, Baudo F, Collins PW, Knoebl P, Leissinger CA, Tiede A, Kessler CM. Acquired hemophilia A: Updated review of evidence and treatment guidance. Am J Hematol. 2017 Jul;92(7):695-705. doi: 10.1002/ajh.24777. Epub 2017 Jun 5. PMID: 28470674.

Sridharan, M., Pruthi, R.K. Autoimmune (Acquired) Hemophilia: Updates in Diagnosis and Therapy. The Hematologist (2022) 19 (2). https://ashpublications.org/thehematologist/article/doi/10.1182/hem.V19.2.2022214/484175/Autoimmune-Acquired-Hemophilia-Updates-in

INTERNET

Grethlein SJ. Acquired Hemophilia Treatment & Management. Medscape. Last updated March 28, 2022. https://emedicine.medscape.com/article/211186-treatment. Accessed May 15, 2022.


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