Clotting Factor Replacement
Clotting factor replacement therapy is the main treatment for children with hemophilia. This treatment, which is given through a vein with intravenous (IV) infusion or with a small butterfly needle, can increase clotting factor levels and reduce the severity and frequency of bleeding episodes and other symptoms, such as pain and swelling. Clotting factor replacement therapy is also commonly used to prevent complications of severe hemophilia, such as recurrent bleeding into the joints.
Children with hemophilia type B, who are missing clotting factor IX, need infusions twice a week. Children with hemophilia A need infusions of factor VIII three times a week, because the protein does not last as long in the body as factor IX. Researchers are working to develop longer-acting clotting factors, which may reduce the frequency of treatment.
Clotting factor replacement therapy is initially done in the doctor’s office and takes only a few minutes. When a family is ready, the team sends visiting nurses to perform these infusions in your home. Doctors and nurse practitioners at Hassenfeld Children’s Hospital and the home nursing staff can teach parents how to give their child infusions, so that the nurse visits are no longer necessary. Eventually, you or a nurse can teach your child how to perform infusions and learn to manage the condition during adolescence and adulthood.
Immune Tolerance Test
Up to 30 percent of people with severe hemophilia type A and less than 3 percent of people with hemophilia type B develop an immune response, or antibodies, to the clotting factors used in replacement therapy. These antibodies, also called inhibitors, recognize the clotting factor as a foreign substance that needs to be destroyed, making treatment less effective. The risk of developing these antibodies decreases after your child has used clotting factor replacement therapy for a long period of time.
Before beginning clotting factor replacement therapy, the doctor may perform a blood test to determine if your child has antibodies to clotting factor replacement therapy. If he or she has these antibodies, the test may be repeated to determine how long the clotting factor replacement survives in the presence of these antibodies.
The doctor sends the blood sample to a laboratory that specializes in testing for clotting factor inhibitors. Results are available within 24 hours. If your child’s immune response is mild—meaning he or she makes some antibodies to the clotting factor—the doctor may increase the dose to overwhelm the immune system, increasing the therapy’s effectiveness. If your child develops a high number of antibodies to the clotting factor, the doctor may prescribe a different type of clotting factor.
Immune Tolerance Therapy
A doctor may use immune tolerance therapy, also known as immune tolerance induction, to eliminate antibodies to a clotting factor. In one approach, a doctor gives large doses of the clotting factor to your child, by itself or in combination with medications such as corticosteroids and rituximab, or Rituxan®, which suppress the immune system, for months. A child may receive immune tolerance therapy for several years.
Immune tolerance therapy is effective for many children who have an immune reaction to clotting factor. It is more likely to succeed in children with fewer antibodies and when treatment begins shortly after an immune response is detected. The main side effects are an increased risk of infections from immunosuppressant medications and pain and bruising at the injection site.
Desmopressin is a synthetic hormone that stimulates the release of von Willebrand factor, a clotting factor that is stored in the lining of blood vessels. Our doctors may recommend this medication, which is available as a nasal spray or with an injection, for children over age two who have mild hemophilia type A to control bleeding before surgery or dental procedures. Doctors can also inject desmopressin after an injury to stop bleeding. Before prescribing desmopressin, the doctor conducts blood tests to ensure your child responds to the medication.
Common side effects include headaches, flushing, low blood pressure, and a temporary increase in heart rate.
To help with blood clotting, doctors may prescribe clot stabilizers, also known as antifibrinolytic medications. These medications block the production of plasmin, a substance that destroys blood clots. They also prevent the breakdown of fibrin, which maintains the stability of a clot.
Clot stabilizers are effective in preventing excessive bleeding in the nose and mouth, and in children with mild to moderate hemophilia A or B. Children can take these medications by mouth or with an IV infusion before medical or dental procedures.
These medications can cause nausea, vomiting, and excessive clotting, in which clots form in blood vessels, a serious complication.
Our specialists see babies every few weeks to help parents adjust to the diagnosis and treatment. As you and your child become comfortable with the treatment, you may return for follow-up appointments every six months. Some blood tests may be repeated during follow-up visits.