Welcome to the Exeter Clinical Laboratory International website
NHS logo

Infliximab Antibody Levels

Blood Sciences Test



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: https://www.exeterlaboratory.com/biotin-alert-potential-assay-interference/


  • Perry M, Bewshea C, Brown R, So K, Ahmad T, McDonald T. Infliximab and adalimumab are stable in whole blood clotted samples for seven days at room temperature. .Ann Clin Biochem.2015 Mar 16. pii: 0004563215580001. [Epub ahead of print]


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

We now also have the option to use NPEx for referral requesting.

Further information about sample requirements for this test can be found here: Infliximab and Anti-Infliximab Antibodies – further information

Specimen Labelling Procedure


Specimen Labelling Procedure
University of Exeter logo
UKAS Medical logo


Royal Devon University Healthcare logo