Definition of Nitroblue tetrazolium test:

The nitroblue tetrazolium test looks to see if certain immune system cells can change a colorless chemical called nitroblue tetrazolium (NBT) into a deep blue color.

How the test is performed:

A blood sample is needed. For information on how this is done, see: Venipuncture

In the laboratory, the chemical NBT is added to a sample of white blood cells. The laboratory specialist looks at the cells under a microscope and determines if the NBT made them turn blue.

How to prepare for the test:

If your child is to have this test performed, it may be helpful to explain how the test will feel, and even demonstrate on a doll. Explain the reason for the test. Knowing the "how and why" may reduce the anxiety your child feels.

How the test will feel:

When the needle is inserted to draw blood, you may feel moderate pain or only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed:

This test is done to screen for chronic granulomatous disease. This disorder is passed down in families. In people who have this disease, certain immune cells do not help protect the body from infections.

People who have frequent infections in the bones, skin, joints, lungs, and other parts of the body may have this test done.