Pathology Handbook

NBT Reduction Test


Nitroblue tetrazolium reduction test

Clinical Indications

(specialist request only)

When Chronic granulomatous disease is suspected (CGD): history of recurrent or severe staphylococcal infections/abscesses or infections with other gram positive bacteria, invasive fungal infections (when other causes of immunodeficiency have been excluded), multiple granulomatous lesions.

Test Includes

Assay measures the phagocytic activity of polymorphonuclear leucocytes by the amount of colour change of NBT.

Request Form 

Request via ICE.


Assay performed as required.

Specific Criteria

It is essential to provide relevant clinical information.

It is essential to telephone laboratory to arrange the test.

Patient Preparation

No special preparation is required but a travel control is essential

Turnaround Time

Samples are sent to the  referral laboratory immediately on receipt and tested the same day.




4.5 ml


Vacutainer purple top


Samples should be transported to the laboratory immediately.

Lab Handling

Aliquot and store at 4-8°C prior to testing and at -20°C or below for up to 1 month after receipt.

Causes for Rejection

Unlabelled/inadequately labelled sample

Inadequately completed request form

Delay in sample reaching laboratory.

Reference Range

Assay is reported as a percentage of polymorphic leucocytes that contain blue dye particles. Patients with CGD will have very low or zero values, female carriers will have an intermediate level of expression.