Nitroblue tetrazolium test is a blood test that measures the ability of the immune system to convert the colorless nitroblue tetrazolium (NBT) to a deep blue. This test is performed as a screen for chronic granulomatous disease (CGD). If an individual has CGD, the white cells in their blood will not turn blue when exposed to the NBT.
Review Date 2/28/2023
Updated by: Jacob Berman, MD, MPH, Clinical Assistant Professor of Medicine, Division of General Internal Medicine, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.