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Infliximab Activity (with Neutralizing Antibody)

Item Value
Available Stat? No
Test code IFXAN
Performed by ARUP
Sendout? Yes
Method Cell Culture/Quantitative Chemiluminescent Immunoassay/ Semi-Quantitative Chemiluminescent Immunoassay
Collection Instructions Collect specimens before infliximab treatment.
Container type SST or Red-top tube
Amount to Collect 2 mL
Sample type Serum
Preferred volume 1 mL
Min. Volume 0.3 mL
Processing notes Aliquot and freeze. Send to CB frozen. Order ARUP test code 2008320.
Ref Lab Rejection Criteria Contaminated, hemolyzed, icteric, or lipemic specimens.
Normal range
Synonyms Remicade
Stability After separation from cells: Ambient: 48 hours; Refrigerated: 4 weeks; Frozen: 1 year (avoid repeated freeze/thaw cycles)
Turn around times 3 - 5 days
Additional information This test measures the capacity of infliximab to neutralize TNF-activity. Additionally, infliximab neutralizing antibodies (NAb) are titered (reporting the highest dilution of patient sera in which NAb activity is detected).

This test is used to evaluate secondary response failures to infliximab therapy. Secondary response failure is defined as loss of clinical response after initial improvement of clinical signs and symptoms. Therapeutic decision should rest on both the clinical response and the knowledge of the fate of the drug including the emergence of immunogenicity in individual patients.

Circulating infliximab levels have been shown to vary considerably between patients. These differences relate to route and frequency of administration and patient-related features such as age, gender, weight, drug metabolism, and concomitant medications such as methotrexate and other immunosuppressants.

IF Infliximab
Activity is.... AND Infliximab Neutralizing
Ab. Titer is.... THEN....
Not Detected Not Detected A higher dosage of infliximab or shortening the dosing interval may be appropriate.
Not Detected 1:20 or greater A change to another anti-TNF-a drug may be appropriate.
0.65 ug/mL or greater Not Detected A change to another type of therapy (not targeting TNF-a) may be appropriate.
0.65 ug/mL or greater 1:20 or greater Repeat testing is suggested to rule out decreasing infliximab activity and/or increasing infliximab neutralizing antibodies.


CPT coding 86352-90 x 2
LOINC code 39803-2, 72623-2, 11526-2
Last Updated 11/29/2016 9:11:37 AM
Entry Number 1716
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