Clotting factor replacement for hemophilia
Hemophilia is primarily treated by replacing the absent or abnormal clotting factors to prevent severe blood loss and complications from bleeding. Clotting factors are replaced by injecting (infusing) a clotting factor replacement into the veins. Infusions of clotting factors help blood to clot normally and prevent damage to muscle, joints, and organs. There are different types of blood clotting factor replacement.
Fresh frozen plasma (FFP)
Fresh frozen plasma is the liquid part of blood (plasma) taken from a donor and frozen for later use. It contains all types of clotting factors so it can be used to treat a variety of bleeding problems, including hemophilia.
Fresh frozen plasma is less expensive than donated and recombinant factor concentrates. But very large volumes of plasma are needed to provide enough clotting factor to prevent bleeding. This amount of plasma is not easily kept at home.
Cryoprecipitate (concentrated frozen plasma)
Cryoprecipitate contains all clotting factors, so it can be used to treat many varieties of blood disorders. It is used to treat people who have unidentified clotting problems. Cryoprecipitate is not likely to transmit a disease, because it is from only one donor.
A bleeding episode requires less cryoprecipitate than fresh frozen plasma because cryoprecipitate has been concentrated. But compared to factor concentrates and recombinant products, a relatively large amount of cryoprecipitate is still required to increase clotting factors to a safe level.
Cryoprecipitate must be frozen, so it is not easily kept at home.
Cryoprecipitate is less expensive than donated and recombinant factor concentrates.
In the past, in order to get enough clotting factors, a person with hemophilia had to be injected with large amounts of plasma. Clotting factor concentrates have changed this by providing large amounts of clotting factor in smaller doses. Clotting factor is collected from donors or is produced in a lab (using recombinant DNA technology) and concentrated into a powder form that is then mixed with sterile water and injected.
Donated factor concentrates are made specifically for one type of hemophilia. Factor VIII concentrates treat hemophilia A, and factor IX concentrates treat hemophilia B. It requires relatively small amounts of factor concentrates to bring clotting factors in the blood to a normal level. These products can be kept and used at home.
Factor concentrates come in a variety of purities. The purer the concentrate, the more of the specific factor it contains compared to other clotting factors and the better it will work, but the more expensive it will be. Factor concentrates are expensive compared to fresh frozen plasma and cryoprecipitate.
Lab-produced (recombinant) factor concentrates are a type of recombinant clotting factor produced for hemophilia B that does not contain any human or animal products, so there is almost no risk of contracting a virus. Relatively small amounts of factor concentrates are required to bring clotting factors in the blood up to normal levels. These products come in powder form, so they can be kept and used at home. They are mixed with sterile water that comes with the concentrate and then injected. But they are very expensive, and shortages of recombinant concentrates occur more frequently than with other forms of clotting factor.
What To Expect After Treatment
The infusion of clotting factor stops bleeding within hours, although the exact amount of time varies. Heavy bleeding takes longer to control than light bleeding. If the proper amount of replacement factors is given, bleeding will stop normally.
Why It Is Done
People with hemophilia can use clotting factors to treat bleeding episodes or to prevent bleeding before surgeries and activities that may cause bleeding. People with severe hemophilia may need to infuse clotting factors regularly (3 times a week) to prevent spontaneous bleeding in joints and muscles. The person with hemophilia should learn how to self-infuse with replacement clotting factors. By the age of 10, most children with hemophilia should be able to infuse themselves.
How Well It Works
If a person with hemophilia is treated quickly, the blood will clot normally, and bleeding will not damage the muscles and joints.
Some people who have hemophilia A develop inhibitors to clotting factors. When this occurs, the usual forms of clotting factors may not effectively prevent or stop bleeding.
What To Think About
- To stop internal bleeding from causing long-term damage to joints, a person who has hemophilia must replace clotting factors promptly.
- There is little risk of getting viruses such as the human immunodeficiency virus (HIV), hepatitis B, or hepatitis C from clotting factors that use donated blood products (fresh frozen plasma, cryoprecipitate, or donated factor concentrates). In the past, the spread of viruses through donated blood products sometimes caused serious complications for people who have hemophilia. Donors now are carefully screened, and donated blood goes through purifying processes that kill viruses.
- Hepatitis A and parvovirus (the virus that causes fifth disease) can still sometimes be transmitted when using clotting factors made from donated blood (fresh frozen plasma, cryoprecipitate, or a donated factor concentrate). These viruses are difficult to detect and destroy because of their molecular structure.
- Children are more likely to develop antibodies (inhibitors) to clotting factors than adults.
- Injecting clotting factors regularly is expensive, but it is effective in preventing joint damage. Because clotting factor must be injected into a vein every few days, it may be difficult to stay on schedule with the injections.