Infliximab Concentration and Anti-Infliximab Antibody

CPT: 80299; 82397
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Test Details

Synonyms

  • Anti-TNF-alpha Drug
  • IFD
  • Remicade

Use

Provides infliximab drug concentration levels as well as levels of anti-infliximab antibodies.

Limitations

Failure of infliximab therapy may not always be due to the presence of anti-infliximab antibodies. In addition, the absence of anti-infliximab antibodies does not guarantee positive response to treatment.

Methodology

Electrochemiluminescence immunoassay (ECLIA)

Reference Interval

See table.

Infliximab drug level:

<0.4 µg/mL

• Result ≥0.4 µg/mL indicates detection of infliximab.

• In the presence of anti-infliximab antibodies, the infliximab drug level reflects the antibody-unbound fraction of infliximab concentration in serum.

Anti-infliximab antibody:

<22 ng/mL

• Result ≥22 ng/mL indicates detection of anti-infliximab antibodies.

Additional Information

In the absence of anti-infliximab antibodies, the infliximab drug level typically reflects the total infliximab concentration in serum. In the presence of anti-infliximab antibodies, the infliximab drug level typically reflects the antibody-unbound fraction of infliximab concentration in serum. The presence of infliximab drug, even at concentrations well above target treatment levels (>50 μg/mL), does not interfere with the anti-infliximab antibody detection. This assay may be helpful for any patients on infliximab therapy for diseases such as Crohn's disease, inflammatory bowel disease, ulcerative colitis, rheumatoid arthritis, or other autoimmune conditions.

Specimen Requirements

Specimen

Serum

Volume

2 mL

Minimum Volume

1 mL (Note: This volume does not allow for repeat testing.)

Container

Red-top tube or gel-barrier tube

Collection

Allow a minimum clotting time of 30 to 60 minutes with serum separation within 2 hours of collection. Send serum in a plastic transport tube. To avoid delays in turnaround time when requesting multiple tests on frozen samples, please submit separate frozen specimens for each test requested.

Storage Instructions

Frozen (preferred) or refrigerated; stable for seven days. Stable at room temperature or refrigerated for seven days. Freeze/thaw cycle: stable x6

Clinical Information

Special Instructions

To order this test with the serial monitor service, use test 503870 .

LOINC® Map

Order Code Order Code Name Order Loinc Result Code Result Code Name UofM Result LOINC
503770 Infliximab (IFX) Conc+ IFX Ab 503772 Infliximab Drug Level ug/mL 39803-2
503770 Infliximab (IFX) Conc+ IFX Ab 503773 Anti-Infliximab Antibody ng/mL 72623-2
503770 Infliximab (IFX) Conc+ IFX Ab 503774 Infliximab (IFX) Conc+IFX Ab N/A

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