Infliximab Level with Antibody Reflex (Sendout)

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General Information

Lab Name
Infliximab Level with Antibody Reflex (Sendout)
Lab Code
RINFXR
Epic Name
Infliximab Level with Antibody Reflex (Sendout)
External Test Id
INFXR
Description

Useful For: Trough level quantitation for evaluation of patients undergoing therapy with infliximab, infliximab-dyyb, infliximab-abda or infliximab-axxq.

Test Algorithm: Infliximab will be performed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) on all samples. When Infliximab results are below 5.1 mcg/mL, testing for antibodies to infliximab will be performed at an additional charge.

Patient Preparation:

  1. For 12 hours before specimen collection do not take multivitamins or dietary supplements containing biotin (vitamin B7), which is commonly found in hair, skin, and nail supplements and multivitamins.
  2. Draw blood immediately before next scheduled dose (trough specimen).

***Alert: Due to reagent issues at Mayo Clinic laboratories, test results for the Infliximab antibody reflex test will be delayed. The estimated duration of this delay is anticipated to be 2-4 weeks. Notification will be sent when standard testing resumes.***

References

  1. Ordas I, Mould DR, Feagan BG, Sandborn WJ: Anti-TNF monoclonal antibodies in inflammatory bowel disease: pharmacokinetics-based dosing paradigms. Clin Pharmacol Ther. 2012 Apr;91(4):635-646. doi: 10.1038/clpt.2011.328

  2. Feuerstein JD, Nguyen GC, Kupfer SS, et al: American Gastroenterological Association Institute guideline on therapeutic drug monitoring in inflammatory bowel disease. Gastroenterology. 2017 Sep;153(3):827-834. doi: 10.1053/j.gastro.2017.07.032

  3. Mayo Clinical & Interpretive Information: Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum
Synonyms
Anti-Infliximab Antibody, Anti-TNF inhibitor, Avsola, Inflectra, Infliximab abda, Infliximab Antibody, Infliximab Level, INFXR, Inxab, Ixifi, Remicade, Renflexis
Components
Code Name
RINFX Infliximab Drug Level
RINFXI Infliximab Interpretation

Interpretation

Method

Infliximab Level: Selective Reaction Monitoring Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)

Anti-Infliximab Antibody: Electrochemiluminescent Bridging Immunoassay with Acid Dissociation

Reference Range
See individual components
Interferences and Limitations

Cautions:

Toxicity effects other than acute hypersensitivity infusion reactions have not been described nor correlated with infliximab concentrations.

During the initial induction phase of treatment (weeks 0, 2, and 6), steady-state has not been achieved and concentrations of infliximab may vary significantly between infusions.¹

Therapeutic concentrations of infliximab may vary according to the disease (eg, Crohn disease versus ulcerative colitis versus rheumatoid arthritis).

The American Gastroenterology Association established thresholds associated with positive outcomes for adults with active inflammatory bowel disease based on several clinical studies.²

Samples containing more than 12.5 ng/mL biotin (vitamin B7) may interfere (in the form of depressed signal) with INXAB / Infliximab Antibodies, Serum.

For antibodies-to-infliximab (ATI), pediatric and adult reference ranges were validated, and the presence of an ATI is established as greater than or equal to 50 U/mL by our bridging electrochemiluminescent/acid dissociation method.

The presence of endogenous infliximab is a recognized interference in most ATI methods. This assay includes an acid dissociation step, which partially mitigates this interference. Tolerance up to 12.5 mcg/mL infliximab has been documented, although this is also determined by the titer of the ATI present in the patient sample.

References

  1. Ordas I, Mould DR, Feagan BG, Sandborn WJ: Anti-TNF monoclonal antibodies in inflammatory bowel disease: pharmacokinetics-based dosing paradigms. Clin Pharmacol Ther. 2012 Apr;91(4):635-646. doi: 10.1038/clpt.2011.328

  2. Feuerstein JD, Nguyen GC, Kupfer SS, et al: American Gastroenterological Association Institute guideline on therapeutic drug monitoring in inflammatory bowel disease. Gastroenterology. 2017 Sep;153(3):827-834. doi: 10.1053/j.gastro.2017.07.032

  3. Mayo Clinical & Interpretive Information: Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum

Ordering & Collection

Specimen Type
Blood
Collection

Patient Preparation: Draw blood immediately before next scheduled dose (trough specimen).

Collection: 6 mL blood in a plain, RED TOP tube

  • Unacceptable: Any other tube type. Gel tubes/SST are not acceptable.
Handling Instructions

Outside Laboratories: Centrifuge sample and transfer 1 mL (0.5 mL min) serum to a separate aliquot within 2 hours of collection. Refrigerate serum.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: Unacceptable.

Reject Due To: Gross hemolysis, gross icterus. Gross lipemia is acceptable.

Quantity
Requested: 1 mL serum
Minimum: 0.5 mL serum

Processing

Receiving Instructions

Centrifuge sample and transfer 1 mL (0.5 mL min) serum to a separate plastic vial within 2 hours of collection. Refrigerate serum.

Sendouts:

  • Order Mayo Test: INFXR.
  • Interfaced: Yes [Interface: 601; Department: MARF]

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: Unacceptable.

Reject Due To: Gross hemolysis, gross icterus. Gross lipemia is acceptable.

Misc Sendout

Performance

Lab Department
Sendouts Mayo Lab (RF)(MARF)
Frequency
Performed: Monday, Wednesday, Thursday at 4pm. Maximum Laboratory Time: 6 days
Available STAT?
No
Performing Location(s)
Sendout Mayo Clinic Laboratories (Superior Drive)
800-533-1710

3050 Superior Drive NW
Rochester, MN 55901

Billing & Coding

CPT Codes
80230
LOINC
39803-2
Interfaced Order Code
UOW3976