Coagulation Defects - Hemophilia A

Hemophilia A - overview

Hemophilia A is a hereditary bleeding disorder caused by a lack of blood clotting factor VIII. Without enough factor VIII, the blood cannot clot properly to stop bleeding.

Causes

Hemophilia A is caused by an inherited X-linked recessive trait, with the defective gene located on the X chromosome. Females have two copies of the X chromosome. So if the factor VIII gene on one chromosome does not work, the gene on the other chromosome can do the job of making enough factor VIII. Males have only one X chromosome. If the factor VIII gene is missing on a boy's X chromosome, he will have hemophilia A. For this reason, most people with hemophilia A are male. If a woman has a defective factor VIII gene, she is considered a carrier. This means the defective gene can be passed down to her children. Boys born to such women have a 50% chance of having hemophilia A. Their daughters have a 50% chance of being a carrier. All female children of men with hemophilia carry the defective gene. Risk factors for hemophilia A include: Family history of bleeding Being male

Tests

If you are the first person in the family to have a suspected bleeding disorder, your doctor will order a series of tests called a coagulation study. Once the specific defect has been identified, other people in your family will need tests to diagnose the disorder. Tests to diagnose hemophilia A include: Prothrombin time Bleeding time Fibrinogen level Partial thromboplastin time (PTT) Serum factor VIII activity

Symptoms

The severity of symptoms vary. Bleeding is the main symptom of the disease. It is often first seen when an infant is circumcised. Other bleeding problems are seen when the infant starts crawling and walking. Mild cases may go unnoticed until later in life. Symptoms may first occur after surgery or injury. Internal bleeding may occur anywhere. Symptoms can include: Bleeding into joints with associated pain and swelling Blood in the urine or stool Bruising Gastrointestinal tract and urinary tract hemorrhage Nosebleeds Prolonged bleeding from cuts, tooth extraction, and surgery Spontaneous bleeding

Treatment

Treatment includes replacing the missing clotting factor. You will receive factor IX concentrates. How much you get depends on: Severity of bleeding Site of bleeding Your weight and height Mild hemophilia may be treated with desmopressin (DDAVP), which helps the body release factor VIII that is stored within the lining of blood vessels. To prevent a bleeding crisis, people with hemophilia and their families can be taught to give factor VIII concentrates at home at the first signs of bleeding. People with severe forms of the disease may need regular preventive treatment. Depending on the severity of the disease, DDAVP or factor VIII concentrate may be given before having dental extractions or surgery in order to prevent bleeding. You should get the hepatitis B vaccine. People with hemophilia are more likely to get hepatitis because they may receive blood products. Patients who develop an inhibitor to factor VIII may require treatment with other clotting factors such as factor VIIa, which can help with clotting, even without any factor VIII.