Hemophilia B - Factor IX Deficiency
Understanding Hemophilia B
Hemophilia B, also known as Christmas disease, is a less common form of hemophilia, much rarer than hemophilia A. A hereditary disorder, it is caused by a deficiency of blood plasma protein called factor IX (FIX), without which the blood cannot clot properly.
Hemophilia B is typically treated by infusing FIX concentrates to replace the defective clotting factor. The amount infused depends upon the severity of bleeding, the site of the bleeding, and the weight of the patient.
Symptoms of Hemophilia B
People with hemophilia B 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 how serious the bleeds are depends on how much FIX is in the plasma, the straw-colored fluid portion of blood.
Normal plasma levels of FIX 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 B. 6% up to 49% of FIX in the blood.
People with mild hemophilia B typically 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 B. 1% up to 5% of FIX in the blood.
People with moderate hemophilia B tend to have bleeding episodes after injuries. Bleeds that occur without obvious cause are called spontaneous bleeding episodes.
- Severe hemophilia B. <1% of FIX in the blood.
People with severe hemophilia B experience bleeding following an injury and may have frequent spontaneous bleeding episodes, often into their joints and muscles.
Diagnosing Hemophilia B
The best place for patients with hemophilia to be diagnosed and treated is 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, dieticians 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 B
The main medication to treat hemophilia B is concentrated FIX product, called clotting factor or simply factor. Recombinant factor products, which are developed in a lab through the use of DNA technology, preclude the use of human-derived pools of donor-sourced plasma. And while plasma-derived FIX products are still available, approximately 75% of the hemophilia community takes a recombinant FIX product.
These factor therapies are infused intravenously through a vein in the arm or a port in the chest. The Medical and Scientific Advisory Council (MASAC) of the National Hemophilia Foundation encourages the use of recombinant clotting factor products. Your doctor or your HTC will help you decide which is right for you.
Patients with severe hemophilia may be on a routine treatment regimen, called prophylaxis, to maintain enough clotting factor in their bloodstream to prevent bleeds. MASAC recommends prophylaxis as optimal therapy for children with severe hemophilia B. 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 result in fewer infusions. Your doctor or your HTC will help you formulate a treatment plan to decide which factor product and dosing regimen is right for you.
Aminocaproic acid is an antifibrinolytic, preventing 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.
- Centers for Disease Control and Prevention
- National Hemophilia Foundation
- National Heart, Lung and Blood Institute
- World Foundation of Hemophilia
This content is not intended to substitute professional medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.
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