Measuring Inhibitors

A doctor might think someone with hemophilia may have an inhibitor if treatments stop working as well as they once did, or when it takes more treatments than usual to control a bleed.4,6

Screening for Inhibitors

A special blood test, called the Nijmegen-modified Bethesda inhibitor assay, is used to check for inhibitors in the blood.4

Measuring Inhibitor Levels

Results of this test can help your doctor, nurse, and hemophilia care team decide on the best treatment plan.4

Understanding Inhibitor Levels

The amount of inhibitors in the blood varies from person to person. Levels can also vary over time.3

The Nijmegen-modified Bethesda test result tells the hemophilia care team whether the amount of inhibitors is low titer or high titer. More than 5 BU is considered high titer (high responding), while less than 5 BU is low titer (low responding).4,6

Why Knowing the Inhibitor Levels Is Important

Knowing the titer level is important. It helps the hemophilia care team decide the best type of treatment to use.4

Factor VIII or factor IX often can be used in low responders. In high responders, treatment with these factors is usually not possible. For these patients, another type of treatment called a bypassing agent may be effective.1,4

Changing Inhibitor Levels

Your doctor, nurse, or hemophilia care team may also watch to see if hemophilia treatments change your inhibitor levels over time.1,3

If a low responder's inhibitor levels do not change much after hemophilia treatment, then treatment with either factor VIII or factor IX replacement therapy may be continued.1,4