Hemophilia - Description

Injury to a blood vessel is a serious problem for the body. Blood may begin to leak out of the injured area. The body has developed a mechanism for protecting itself from this kind of damage. The mechanism involves the formation of a blood clot over the injured area to prevent loss of blood.

Blood clotting is a very complicated process. It involves blood cells known as platelets and at least twenty different chemical compounds. The first step in the clotting process is the formation of a temporary plug. The plug is formed of platelets that stick to the damaged area. The plug is soon covered by a more permanent structure consisting of fibrin (pronounced FI-brin). Fibrin is tissue that acts like a permanent patch or bandage on the injured area.

The production of fibrin takes place in a series of steps that requires thirteen different chemicals. These chemicals are known as "clotting factors." In order for fibrin to form, all thirteen clotting factors must be present in the blood.

Hemophiliacs (people who have hemophilia) may lack one or more clotting factors, or their bodies may not make enough of a clotting factor, or the clotting factor may not be made correctly. In any one of these cases, the patient's body is not able to make fibrin. An injury to a blood vessel cannot be properly repaired. Blood continues to escape from the damaged blood vessel.

Various types of hemophilia have been discovered. Each type results from problems with a particular clotting factor. Hemophilia A is the most common form of the disorder. It is caused by a defective clotting factor known as factor VIII. Hemophilia A can range from relatively mild to very severe. The severity of the disorder depends on how much factor VIII the patient's body is able to make.

Individuals with more than 5 percent of normal factor VIII have mild hemophilia. They are likely to experience bleeding problems only when having surgery or dental procedures. Individuals with 1 to 5 percent of normal factor VIII have moderate hemophilia. They may experience bleeding problems if they have a minor injury, such as a fall. Individuals with less than 1 percent of normal factor VIII have severe hemophilia. They may begin bleeding for no reason at all. Surgery and dental procedures can be very dangerous. About half of all hemophiliacs have this form of the disorder.

Hemophilia B is caused by a defective clotting factor known as factor IX. This type of hemophilia is also known as Christmas disease. The range of symptoms of hemophilia B is similar to that of hemophilia A.

Hemophilia C is very rare and is much more mild that hemophilia A or B. It is caused by a defective clotting factor known as factor XI.