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-Learn About Coagulation Disorders
-What are Bleeding Disorders?
 History of Bleeding Disorders
 Types of Bleeding Disorders
 Types of Bleeds
 Bleeding Disorders and Women
 Caring for the Newly Diagnosed Child
 Psychosocial Issues
-Complications, including Inhibitors
-For Consumers
 What is an Inhibitor?
 Who is at Risk for Developing an Inhibitor?
 How Do You Know If You Have an Inhibitor?
-Test Results
 Porcine Factor VIII
 Immune Tolerance
 Treatment Costs and Financial Considerations
 For Providers
 Discussion Group
 Future Therapies
 What are Clotting Disorders?
 Comprehensive Medical Care - Hemophilia Treatment Centers
 Medical and Scientific Advisory Council
 Financial and Insurance Issues
 HANDI, NHF's Information Resource Center
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Test Results

If the results of the Bethesda assay are positive, it means that there is a detectable level of antibodies working against the deficient coagulation factor being produced as a result of being treated with factor. The degree to which this affects a person is measured in "units." Inhibitors are classified into two categories based upon the highest unit level achieved. Those with a 5 or higher Bethesda unit result at any time are usually classified as having a "high responding" inhibitor level; those who measure below 5 units despite repeated exposure to factor concentrate, are classified as having a "low responding" inhibitor level.

People with high responding inhibitor levels often have quick and strong immune system responses directed against factor (VIII or IX), meaning that the inhibitor level can quickly increase to very high levels of antibodies. In some cases, if there is no further exposure to the replacement factor, the levels may drop over a period of months to years, even to an undetectable range. This does not mean that the inhibitor is gone, as it may reappear with further exposure, often times months later.

In cases where a person is said to have a "low responding" inhibitor level, the body's immune response to factor is slow--it produces a persistently low level of antibodies despite the person's continual exposure to factor concentrate.

A positive test result does not mean a person will always have an inhibitor. Treatment for inhibitors may cause them to disappear. Uncommonly, with the passing of time, inhibitors have spontaneously disappeared without treatment. These are often low responding inhibitors and are then classified as transient inhibitors.



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