Infliximab Level for IBD

Test Code
36303


CPT Codes
80230

Preferred Specimen
1 mL serum collected in a red-top tube (no gel)


Patient Preparation
For up to 48 hours before blood draw, do no take multivitamins or dietary supplements containing biotin or vitamin B7.

Minimum Volume
0.3 mL


Instructions
The blood should be drawn just before the next infusion of infliximab to measure the trough drug level.


Transport Temperature
Refrigerated (cold packs)


Specimen Stability
Room temperature: 48 hours
Refrigerated: 7 days
Frozen -20°C: 28 days
Frozen -70°C: 70 days


Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Serum Separator Tube (SST)


Methodology
Enzyme Linked Immunosorbent Assay (ELISA)

FDA Status
This test was developed and its analytical performance characteristics have been determined by Quest Diagnostics. It has not been cleared or approved by FDA. This assay has been validated pursuant to the CLIA regulations and is used for clinical purposes.

Setup Schedule
Set up: Mon, Tues, Thurs-Sat; Report available: 2-3 days


Reference Range
See Laboratory Report


Clinical Significance
When treatment of inflammatory bowel disease with infliximab or its biosimilar fails, a physician may need to consider treatment options, such as adjusting dose or dosing intervals, switching to a different TNF blocker, or switching to a different drug agent, i.e. a non-TNF blocker. This assay specifically measures serum infliximab and infliximab-dyyb (inflectra) levels. The American Gastroenterological Association (AGA) recommends optimal infliximab trough concentration of 5 mcg/mL or greater in patients with active IBD. Data from separate clinical studies suggest an optimal infliximab trough concentration of greater than 3.8 or 6-10 mcg/mL.
Based on the results of clinical equivalence studies, the FDA and the AGA advocate applying infliximab clinical guidance to the use of its biosimilars.


Performing Laboratory
Quest Diagnostics Nichols Institute-San Juan Capistrano, CA
33608 Ortega Highway
San Juan Capistrano, CA 92675-2042




The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.