Factor replacement therapy is a treatment for hemophilia and von Willebrand disease. It replaces a missing protein in the blood to improve blood clotting.

Factor replacement therapy can help people with bleeding disorders reduce their chances of developing serious bleeding episodes. Most people with severe hemophilia receive prophylactic, or protective, factor replacement therapy to prevent bleeding before it starts.

People with milder hemophilia may receive on-demand injections to help stop extended bleeding episodes after they start.

Read on to learn more about factor replacement therapy, including how it’s used to treat bleeding disorders, and potential side effects.

Blood clotting factors are proteins and other molecules dissolved in your blood that help your blood clot when your blood vessels are injured.

People with hemophilia and other bleeding disorders don’t produce enough of these proteins, which causes excessive bleeding and bruising.

Factor replacement therapy replaces the missing protein in your blood so your blood clots properly.

People with hemophilia now have life expectancies similar to those of people in the larger population. Before factor replacement therapy became available in the 1970s, most people with hemophilia didn’t live into adulthood.

Doctors administer two main types of clotting factors:

  • Plasma-derived factor concentrates: Plasma is a pale yellow liquid that gives your blood its liquidity consistency. Plasma-derived factor concentrate is derived from human blood.
  • Recombinant factor concentrates: Recombinant factor concentrates are artificially created and not derived from human blood. The National Hemophilia Foundation endorses using recumbent factor concentrates to prevent the risk of transmitting bloodborne viruses.

Factor replacement is a treatment option for people with bleeding conditions such as:

DiseaseMissing protein
hemophilia Afactor VIII
hemophilia Bfactor IX
von Willebrand diseasevon Willebrand factor and factor VIII

Replacement therapy may not be needed if you have mild hemophilia. It’s currently the gold-standard treatment option for people with severe hemophilia A.

Severe hemophilia A is defined as having less than 1% blood factor VIII activity.

The medication desmopressin is often the first treatment for people with von Willebrand disease.

Factor replacement therapies are the main treatments when desmopressin does not work.

Factor replacement therapy is administered through regular injections where the missing clotting factor is slowly infused into one of your veins. It’s often injected into a vein in your arm.

These infusions take about 5–10 minutes. You can get the infusion at a clinic or at home. With training from your healthcare team, you may be able to perform the infusions yourself.

Factor replacement therapy is administered either prophylactically (as a preventive) before bleeding occurs or on-demand to treat bleeding episodes after they occur.

The National Bleeding Disorders Foundation recommends prophylaxis for all people with severe hemophilia A.

You may receive one of two types of replacement therapies:

  • Standard half-life: Factor levels spike immediately after receiving a standard half-life therapy but decrease quickly over a couple of days. Injections usually need to be administered two to four times per week.
  • Extended half-life: Extended half-life therapy also causes a spike in your factor levels, but they stay higher for longer than with standard half-life therapy. Usually, you receive extended half-life medications once or twice per week.

The most significant complication of factor replacement therapy is the development of inhibitors.

Inhibitors are antibodies your immune system produces that bind to the injected clotting factors. This binding reduces the effectiveness of your treatment. It increases your risk of severe bleeding.

According to the World Federation of Hemophilia, inhibitors develop in about 20–30% of people with hemophilia A and 3–5% of people with hemophilia B who receive replacement therapy.

Inhibitors typically develop within the first 75 days. If you develop inhibitors, you’re no longer eligible for factor replacement therapy.

Plasma-derived factor concentrates also have a small risk of transmitting bloodborne viruses, such as HIV or viral hepatitis.

According to the National Bleeding Disorders Foundation, the average annual cost of clotting factor therapies for a person with severe hemophilia is roughly $300,000. The overall cost of medical treatment can be twice that.

Treatment can be cheaper for people with milder forms of hemophilia.

If inhibitors form, the cost is often over $1 million per year.

Insurance providers may cover the cost of factor replacement therapy, but they usually charge high deductibles or coinsurance, where you have to cover a percentage of the total treatment cost.

Health insurance providers in the United States cannot deny coverage on the basis of a preexisting health condition such as hemophilia.

Contact the National Bleeding Disorders Foundation for more information about your condition and potential resources available to help cover the cost of treatment.

Factor replacement therapy is a treatment option for bleeding disorders such as hemophilia and von Willebrand disease. It involves injecting missing proteins into your blood to help your blood clot. These proteins may come from human blood or be made in a laboratory.

Replacement therapy can be very expensive and usually costs hundreds of thousands of dollars a year. Talk with your doctor about the cost of your therapy and whether financial assistance is available.