What is hemophilia?
Hemophilia is a raregeneticbleeding disorder that almost always occurs in
males. A person has hemophilia when he or she inherits problems with certain
blood clotting factors, making them unable to work properly.
Blood-clotting factors are needed to help stop bleeding after a cut or injury
and to prevent spontaneous bleeding.
The hemophilia gene can
contain many different errors, leading to different degrees of abnormality in
the amount of clotting factor produced. A person with hemophilia often needs
treatment to prevent severe blood loss and stop internal bleeding.
There are two major types of hemophilia, although the symptoms are the
- Hemophilia Ais caused
by a deficiency of active clotting factor VIII (8). Approximately 1 out of
every 5,000 male babies is born with hemophilia A.1
- Hemophilia B(Christmas
disease) is caused by a lack of active clotting factor IX (9). It is less
common, occurring in 1 out of every 30,000 male babies.1
Hemophilia is usually classified by how severe it is.
There are three levels of hemophilia, although they can overlap. The severity
of the disease is defined by how much clotting factor is produced and in what
situations bleeding most often occurs.
- Mild hemophilia:Clotting factor VIII or clotting factor IX level is 5% of normal or greater.
Mild hemophilia might not be recognized unless there is excessive bleeding
after a major injury or surgery.
- Moderate hemophilia:Clotting factor
VIII or clotting factor IX level is 1% to 5% of normal. Bleeding usually
follows a fall, sprain, or strain.
- Severe hemophilia:Clotting factor VIII or clotting factor IX level is less
than 1% of normal. Bleeding often happens one or more times a week for no
apparent reason (spontaneously).
The percentage of clotting factors stays about the same
throughout a person's life. All family members who have hemophilia usually will
have similar forms.
In very rare cases, a person develops a form
of hemophilia, called acquired hemophilia, that is not inherited. If you have
acquired hemophilia, your clotting factors don't work properly because your
body makesantibodiesthat attack them.
What is clotting factor replacement therapy for hemophilia?
Clotting factor concentratescan help
control bleeding in people with hemophilia by helping blood to clot properly.
They do not cure hemophilia or repair damage that may have already occurred,
such as inflammation from repeated episodes of bleeding in the joints. The
severity of hemophilia, the location of the bleeding, and how much bleeding has
already occurred often determines how much clotting factor concentrate is
In the United States, blood products are carefully screened.
Blood that is suspected of being contaminated with a virus, such as thehuman immunodeficiency virus (HIV),hepatitis B, orhepatitis C, is not used. The risk of contracting a
virus from donated factor concentrate is very low. But people who receive many
units of donated factor concentrate over their lives have a slightly increased
risk of being infected with one of these viruses. In addition,hepatitis Avirus and parvovirus (the virus that
causesfifth disease) are harder to detect and can sometimes
be transmitted through donated factor concentrates.
factor concentrates are not always effective, because the body can develop
antibodies calledinhibitors, which destroy the newly introduced factor
VIII or IX.
What are the main types of clotting factor replacement?
Clotting factor replacement therapyis a way to
introduce missing or inadequate amounts of clotting factor VIII or IX
components into your blood. Replacing factor VIII will help blood to clot in
people who have hemophilia A. Replacing factor IX will help blood to clot in
people who have hemophilia B. Clotting factor replacement therapy can be used
two ways: on a regularly scheduled basis, to prevent bleeding episodes; or on
demand, to prevent or control a bleeding episode that has occurred or is likely
Clotting factor replacement therapy comes in three main
forms: fresh frozen plasma, cryoprecipitate, or factor concentrates.
- Fresh frozen plasmais the
liquid part of blood (plasma) taken from a donor and frozen
for later use.
- Fresh frozen plasma contains all types of clotting
factors, so it can be used to treat a variety of bleeding problems. It is less
expensive than factor concentrates.
- A large amount of plasma is
required to provide enough clotting factor to prevent bleeding. It must be
frozen, so it is usually used in a hospital and is not easily kept at
- Cryoprecipitateis a blood product
that contains all clotting factors, so it can be used to treat many varieties
of bleeding disorders.
- A bleeding episode requires less cryoprecipitate than
fresh frozen plasma because cryoprecipitate has been concentrated.
Cryoprecipitate is not likely to transmit a disease because it is from only one
donor. It is less expensive than donated and recombinant factor
- Although cryoprecipitate is concentrated, a
relatively large amount is still required (compared to factor concentrates and
recombinant products) to increase clotting factors to a safe level.
Cryoprecipitate must be frozen, so it is usually used in a hospital and is not
easily kept at home.
- Factor concentratesare used to
prevent or treat bleeding episodes that occur outside a hospital.
- A factor concentrate that is infused on a
regular basis can prevent some bleeding episodes from occurring. If you have a
factor concentrate infusion soon after a bleeding episode begins, it can
prevent bleeding from becoming severe.
- Clotting factor concentrates
are portable, are easily stored, and can be infused at home.
- Donated factor concentrate is derived from screened blood from
many donors and has a high concentration of factor VIII or IX. Donors are
carefully screened, and donated blood goes through purifying processes that
kill most viruses.
- Recombinant clotting factors are produced in a lab
(using recombinantDNAtechnology) and are not derived from donated
blood. Clotting factors for hemophilia A contain some human or animal proteins,
so there is still some risk that they may contain a virus. But the clotting
factors produced for hemophilia B do not contain any human or animal products.
Recombinant clotting factors are much more expensive than clotting factors made
from donated blood.
What are the benefits of regularly scheduled therapy?
You likely will have fewer bleeding episodes, which may be especially
important if you have severe hemophilia. You also will have a lower risk of
serious complications and long-term damage from repeated bleeding episodes into
your muscles or joints.
You may have an improved quality of life.
You could more freely participate in activities and exercises that might
otherwise cause a bleeding injury.
What are the benefits of on-demand therapy?
On-demand therapy is not needed as often as
regularly scheduled treatment, so it is less expensive. Insurance companies are
more likely to pay some of the cost.
You will not have to give
yourself injections as often.
If a bleeding episode is suspected,
prompt on-demand infusions can quickly and effectively control bleeding. You
will likely get familiar with your body and be able to tell when a bleeding
episode has started, even before you have many symptoms.
can be given before activities where there is a high risk of bleeding.
What are the risks of regularly scheduled therapy?
Treatment is expensive, especially when clotting factors
that are produced in a lab are used. Insurance companies do not always cover
the cost of regularly scheduled preventive treatment.
If you use
donated clotting factors, you increase your risk of contracting a viral
Usually the infusions must be scheduled 3 times a week,
which can disrupt your daily activities. In addition, some people may have a
difficult time with the frequent injections.
If you use
recombinant clotting factors that are produced in a lab, supplies may not
always be available. Shortages are more likely to occur with recombinant
clotting factors than with plasma-derived products.
increase your risk of developing an inhibitor.
What are the risks of on-demand therapy?
bleeding is suspected, a quick response may not always be practical or
If you have severe hemophilia with frequent bleeding
episodes, you may not prevent some episodes. As a result, you may develop
complications and long-term damage. Also, some children with severe hemophilia
who have frequent bleeding episodes miss more school than average, which may
cause them to score lower on achievement tests than children who experience
fewer bleeding episodes.2
If you have an
unexpected accident, it may be difficult to treat a bleeding episode.
Serious bleeding, such as after a head injury, poses a great danger. Head
injuries can cause bleeding that may be fatal if they are not treated
If you need more information, see the topicHemophilia.