Infliximab and Antibodies to Infliximab Quantitation
Also known as: IFX PAN
Use
This test is used to monitor infliximab or infliximab biosimilar therapy. It is particularly relevant for patients undergoing treatment for conditions such as Inflammatory Bowel Disease (IBD) and Rheumatoid Arthritis (RA). The test measures both the concentration of infliximab in the serum and the presence of antibodies against infliximab, which can affect the efficacy of the treatment. The results are crucial for adjusting the therapeutic regimen to ensure optimal therapeutic levels and to evaluate the potential development of resistance due to antibodies against the drug.
Special Instructions
Specimen should be collected as a trough specimen, meaning just before the next scheduled dose of infliximab or infliximab biosimilar. Avoid exposure to biotin (vitamin B7) for 12 hours prior to specimen collection to prevent interference with the test results.
Limitations
The test's quantitative limits are significant for interpretation. For infliximab quantitation, a level of 0.5 ug/mL or higher indicates detection of the drug or its biosimilar, but therapeutic levels may vary depending on the disease. Similarly, antibody levels of 20 ng/mL or higher suggest the presence of antibodies against infliximab. However, the presence of antibodies should be interpreted in the context of infliximab trough concentration to determine clinical significance and impact on treatment efficacy. This test has not been cleared or approved by the U.S. Food and Drug Administration but is developed following CLIA guidelines.
New York Approved
Methodology
Immunoassay (ECLIA)
Biomarkers
LOINC Codes
- 86896-8
- 86897-6
Result Turnaround Time
3-7 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.1 mL
Container
Serum separator tube
Collection Instructions
Separate serum from cells ASAP after collection. Transfer 1 mL serum to an ARUP standard transport tube.
Patient Preparation
Collect specimen before the next scheduled dose of infliximab or infliximab biosimilar (trough specimen). Avoid exposure to biotin (vitamin B7) for 12 hours prior to specimen collection.
Storage Instructions
Refrigerated transport is required.
Causes for Rejection
Grossly hemolyzed, icteric, or lipemic specimens.
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 days |
| Refrigerated | 2 weeks |
| Frozen | 1 month |