When you bleed, the body launches a series of reactions that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors. When one or more of these clotting factors are missing, there is usually a higher chance of bleeding.
Hemophilia is caused by a lack of enough factor VIII or IX. In most cases, hemophilia is passed down through families (inherited). It most often affects males.
The main symptom of hemophilia is bleeding. Mild cases may go unnoticed until later in life, when they occur during surgery or after trauma.
In more severe cases, serious bleeding may occur without any cause. Internal bleeding may occur anywhere. Bleeding into joints is common.
Signs and tests
Most often, hemophilia is diagnosed after a person has an abnormal bleeding episode or when there is a known family history of the condition.
Standard treatment involves replacing the missing clotting factor through a vein (intravenous infusions).
Diagnosing a bleeding disorder is important so that the doctor can take extra care if you need surgery, and can test or warn other family members who might be affected.
Ragni MV, Kessler CM, Lozier JN. Clinical aspects and therapy for hemophilia. In: Hoffman R, Benz EJ Jr, Shattil SJ, et al, eds. Hoffman Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Churchill Livingstone Elsevier;2008:chap 2005.
David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.