How does clotting factor work?

People with hemophilia can lead practically normal lives by using medicine, called factor. This medicine, injected into the veins, replaces the factor that does not work properly. It's like replacing the relay runner who dropped out of the race with a new runner who will finish the job. With all the factors working properly, the directions for blood clotting are passed along until the fibrin net is formed.

Factor comes in small bottles and looks like packed white powder. When properly mixed with sterile water, factor is ready to be infused - injected directly into a vein. Sometimes the vein is in the arm; sometimes it is on the back of a hand. When it is infused, factor does not go directly to the site of the bleed; it takes a trip around the body. All veins carry blood back to the heart, so factor goes back to the heart, too. Then the heart pumps factor out to all parts of the body at the same time, including the place that is bleeding. Factor can work quickly to stop a bleed.

Infants and small children with hemophilia are usually infused by doctors and nurses who are experts in hemophilia care. As a child grows older, he can be infused at home by his parents, who are trained by the doctors and nurses. By the time a boy with hemophilia is a teenager, he can infuse himself. An infusion doesn't take long and can be done at home, at school or at work. It's great to be able to self-infuse because a person with hemophilia can go almost anywhere and do many activities knowing that the factor he carries will help stop a bleed quickly.

Adapted from Tell Them the Facts! By Laureen A. Kelley, 1995