Blood Sciences Test

Infliximab Antibody Levels



Special instructions



AU/mL (arbitrary units per mL)

Test Usage

Interpretation of Infliximab antibody levels

General points

This assay measures TOTAL Infliximab Antibody concentration.

Total Antibody concentration >/= 10 AU/mL is positive. The distribution for 3760 positive results is as follows: 

Centile range Total Infliximab antibodies (AU/mL)
0 – 5th 10 – 11
6th – 25th 12 – 18
26th – 50th 19 – 40
51st – 75th 41 -115
76th – 95th 116 – 400
>95th >400

The top of the measuring range is 400 AU/mL. This corresponds to the 95th Centile

For further interpretation please see: Anti TNF monitoring guidance

Biotin Interference

The ELISA immunoassay method used for infliximab total anti-drug antibody measurement at Exeter Blood Sciences laboratory uses a streptavidin-biotin system in its design. If patients are taking large doses of Biotin (Vitamin B7), there is potential for interference in this assay with a possibility of lowered results when biotin concentration >318 nmol/L.

For further information on biotin interference please see:



Local test


10 days

Can be added on to an existing request


We welcome referrals for Anti TNF monitoring. If you are a new requestor please complete the following form: New requestor form

Our Quality Statement for referred work can be found here : Quality statement May 2019 (307 downloads)


Specimen Labelling Procedure