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March 1974

The Nitroblue Tetrazolium Test: An Evaluation of the False-Positive and False-Negative Results

Author Affiliations

Iowa City

From the Department of Internal Medicine (Division of Infectious Diseases) the University of Iowa Hospital, Iowa City.

Arch Intern Med. 1974;133(3):432-436. doi:10.1001/archinte.1974.00320150106013

The nitroblue tetrazolium (NBT) test was done in 378 adult patients studied at the University of Iowa Hospitals. Normal patients had phagocyte values below 8%, or 600 NBT-positive phagocytes per cubic millimeter. Patients with untreated bacterial infections had phagocyte values ranging from 595 to 7,598/cu mm, with a median of 1,577 and a mean value of 2,102 positive phagocytes per cubic millimeter. Of 67 infected patients receiving effective antibacterial medication, 24 had normal NBT tests; phagocyte values for this infected group ranged from 64 to 11,111; median value was 704, and mean value 1,094. Among 19 patients with false-positive tests, active radiotherapy and hemodialysis accounted for half of these reactions. Five of 31 patients studied who had fever and normal NBT tests were considered false-negatives; 26 patients had true-negative tests, including six patients with advanced malignant lymphomas and six with drug fevers. The NBT test was valuable in the evaluation of febrile patients.

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