Understanding Hemophilia A
Hemophilia A, also known as factor VIII deficiency or classic hemophilia, is the most common type of hemophilia. In most cases, it is an inherited disorder in which one of the proteins needed to form blood clots is missing or reduced. In about 30% of cases, there is no family history of the disorder and the condition is the result of a spontaneous gene mutation.
Symptoms of Hemophilia A
People with hemophilia A often bleed longer than other people. Bleeds can occur internally, into joints and muscles, or externally, from minor cuts, dental procedures or trauma. How frequently a person bleeds and the severity of those bleeds depends on how much factor VIII (FVIII) is in the plasma, the straw-colored fluid portion of blood.
Normal plasma levels of FVIII range from 50% to 150%. Levels below 50%, or half of what is needed to form a clot, determine a person’s symptoms.
- Mild hemophilia A – 6% up to 49% of FVIII in the blood
People with mild hemophilia A generally experience bleeding only after serious injury, trauma or surgery. In many cases, mild hemophilia is not diagnosed until an injury, surgery or tooth extraction result in prolonged bleeding. The first episode may not occur until adulthood. Women with mild hemophilia often experience menorrhagia, heavy menstrual periods, and can hemorrhage after childbirth. - Moderate hemophilia A – 1% up to 5% of FVIII in the blood
People with moderate hemophilia A tend to have bleeding episodes after injuries. Bleeds that occur without obvious cause are called spontaneous bleeding episodes. - Severe hemophilia A – <1% of FVIII in the blood
People with severe hemophilia A experience bleeding following an injury and may have frequent spontaneous bleeding episodes, often into their joints and muscles.
Diagnosing Hemophilia A
Many patients with hemophilia are diagnosed and treated at one of the federally-funded hemophilia treatment centers (HTCs) that are spread throughout the country. HTCs provide comprehensive care from skilled hematologists and other professional staff, including nurses, physical therapists, social workers and sometimes dentists, dietitians and other healthcare providers.
A medical health history is important to help determine if other relatives have been diagnosed with a bleeding disorder or have experienced symptoms. Tests that evaluate clotting time and a patient’s ability to form a clot may be ordered. A clotting factor test, called an assay, will determine the type of hemophilia and its severity.
Treating Hemophilia A
The main medication to treat hemophilia A is concentrated FVIII product, sometimes referred to as clotting factor or simply factor. Recombinant factor products are developed in a lab through the use of DNA technology instead of using human-derived pools of donor-sourced plasma. And while plasma-derived FVIII products are still available, most of the hemophilia community uses a recombinant FVIII product. The Medical and Scientific Advisory Council (MASAC) of the National Hemophilia Foundation encourages the use of recombinant clotting factor products.
Factor products are infused intravenously through a vein in the arm or a port in the chest.
Patients with severe hemophilia may follow a routine treatment regimen known as prophylaxis, to maintain enough clotting factor in the bloodstream to prevent bleeding episodes. MASAC recommends prophylaxis as the preferred treatment approach for children with severe hemophilia A. Third generation factor products are manufactured to include fc fusion or PEGylation and have a longer half-life than first- or second-generation products. Use of third generation products may reduce the number of infusions required. Prescribers will help formulate a treatment plan to decide the most appropriate factor product and dosing regimen.
Non-factor replacement therapies help prevent bleeding or assist in better control of bleeding. It is important to note these therapies do not treat bleeds, and factor replacement products may still be needed in the event of a bleed or injury.
- Desmopressin acetate (DDAVP®) is the synthetic version of vasopressin, a natural antidiuretic hormone that helps stop bleeding. In patients with mild hemophilia, it can be used for joint and muscle bleeds, for bleeding in the mucous membranes of the nose and mouth, and before and after surgery. It comes in an injectable form and a nasal spray.
- Aminocaproic acid prevents the breakdown of blood clots. It is often recommended before dental procedures, and to treat nose and mouth bleeds. It is taken orally, as a tablet or liquid. MASAC recommends that a dose of clotting factor be taken first to form a clot, then aminocaproic acid, to preserve the clot and keep it from being broken down prematurely.
- Bispecific Antibody Therapy is used to treat hemophilia A and mimics the way FVIII works. Currently there is one medication of this type, emicizumab (Hemlibra®). Unlike factor replacement therapy, in which the missing factor is injected directly into the vein, emicizumab is given by an injection under the skin as a subcutaneous injection.
- Hormone therapy, such as birth control pills, or oral contraceptives, can be taken to reduce heavy menstrual bleeding. The hormones in birth control pills can increase the levels of FVIII in the blood.
Rebalancing Agents are treatments that work to prevent too much bleeding by blocking proteins that slow down the clotting process.
Gene therapy is a way of treating a genetic disease or disorder by providing people with working copies of the gene to correct the disease or disorder. There are different approaches to gene therapy, including gene transfer and gene editing.
Websites:
- Centers for Disease Control and Prevention
- National Bleeding Disorders Foundation
- National Heart, Lung and Blood Institute
- World Foundation of Hemophilia
- Hope for Hemophilia
Support Groups:
References:
- Bleeding Disorders A-Z | National Bleeding Disorders Foundation
- MASAC Document 267 – MASAC Recommendation Concerning Prophylaxis for Hemophilia A and B with and without Inhibitors | National Bleeding Disorders Foundation
Last reviewed 08/18/2026
