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HelpTest Code INFXR Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum
Useful For
Trough level quantitation for evaluation of patients undergoing therapy with infliximab, with signs and symptoms of loss of response to therapy.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| INFX | Infliximab, S | No | Yes |
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| INXAB | Infliximab Ab, S | No | No |
Testing Algorithm
Infliximab will be performed by liquid chromatography-tandem mass spectrometry on all specimens. When infliximab results are below 5.1 mcg/mL, testing for antibodies to infliximab will be performed at an additional charge.
For more information see Ulcerative Colitis and Crohn Disease Therapeutic Drug Monitoring Algorithm
Reporting Name
Infliximab QN with Reflex to Ab, SSpecimen Type
Serum RedSpecimen Required
Patient Preparation:
1. Draw blood immediately before next scheduled dose (trough specimen).
2. 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.
Collection Container/Tube:
Preferred: Red top
Acceptable: Serum gel
Submission Container/Tube: Plastic vial
Specimen Volume: 1 mL
Collection Instructions: Centrifuge and aliquot serum into plastic vial within 2 hours of collection.
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Serum Red | Refrigerated (preferred) | 28 days | |
| Frozen | 28 days |
Reference Values
INFLIXIMAB QUANTITATION:
Limit of quantitation is 1.0 mcg/mL. Therapeutic ranges are disease specific.
Pediatric reference ranges are not established.
INFLIXIMAB ANTIBODIES
Absence of antibodies to infliximab (ATI) is defined as <50 U/mL
Presence of ATI is reported as positive when concentrations are ≥50 U/mL
Interpretation
Low trough concentrations may be correlated with loss of response to infliximab. For infliximab trough concentrations 5.0 mcg/mL or less, testing for antibodies to infliximab (ATI) is suggested.
For infliximab trough concentrations above 5.0 mcg/mL measured in the setting of loss of response to therapy, patients may benefit from treatment with a different pharmaceutical agent.
Results above 35 mcg/mL are suggestive of a blood draw at a time-point in treatment other than trough.
Interpretation and patient management will be different according to disease state, clinical presentation (symptomatic versus appropriate response to therapy), several other laboratory tests and a combination of the drug concentration and/or presence of ATI.
A low titer ATI is reported with a quantitative value of 50 to 499 U/mL. A high-titer ATI is reported with a quantitative value greater than or equal to 500 U/mL, using the Mayo Clinic assay.
Clinical Reference
1. Colombel JF, Sandborn WJ, Reinisch W, et al. Infliximab, azathioprine, or combination therapy for Crohn's disease. N Engl J Med. 2010;362(15):1383-1395. doi:10.1056/NEJMoa0904492
2. Jurgens M, Mahachie John JM, Cleynen I, et al. Levels of C-reactive protein are associated with response to infliximab therapy in patients with Crohn's disease. Clin Gastroenterol Hepatol. 2011;9(5):421-427.e1. doi:10.1016/j.cgh.2011.02.008
3. Ordas I, Mould DR, Feagan BG, Sandborn WJ. Anti-TNF monoclonal antibodies in inflammatory bowel disease: pharmacokinetics-based dosing paradigms. Clin Pharmacol Ther. 2012;91(4):635-646. doi:10.1038/clpt.2011.328
4. Afif W, Loftus EV Jr, Faubion WA, et al: Clinical utility of measuring infliximab and human anti-chimeric antibody concentrations in patients with inflammatory bowel disease. Am J Gastroenterol. 2010;105(5):1133-1139. doi:10.1038/ajg.2010.9
5. Imaeda H, Bamba S, Takahashi K, et al. Relationship between serum infliximab trough levels and endoscopic activities in patients with Crohn's disease under scheduled maintenance treatment. J Gastroenterol. 2014;49(4):674-682. doi:10.1007/s00535-013-0829-7
6. Steenholdt C, Bendtzen K, Brynskov J, Thomsen OO, Ainsworth MA.: Cut-off levels and diagnostic accuracy of infliximab trough levels and anti-infliximab antibodies in Crohn's disease. Scand J Gastroenterol. 2011;46(3):310-318. doi:10.3109/00365521.2010.536254
7. Syversen SW, Jorgensen KK, Goll GL, et al. Effect of Therapeutic Drug Monitoring vs Standard Therapy During Maintenance Infliximab Therapy on Disease Control in Patients With Immune-Mediated Inflammatory Diseases: A Randomized Clinical Trial. JAMA. 2021;326(23):2375-2384. doi:10.1001/jama.2021.21316
8. Feuerstein JD, Nguyen GC, Kupfer SS, Falck-Ytter Y, Singh S; American Gastroenterological Association Institute Clinical Guidelines Committee. American Gastroenterological Association Institute guideline on therapeutic drug monitoring in inflammatory bowel disease. Gastroenterology. 2017;153(3):827-834. doi:10.1053/j.gastro.2017.07.032
9. Silva-Ferreira F, Afonso J, Pinto-Lopes P, Magro F. A systematic review on infliximab and adalimumab drug monitoring: Levels, clinical outcomes and assays. Inflamm Bowel Dis. 2016;22(9):2289-2301. doi:10.1097/MIB.0000000000000855
10. Willrich MA, Murray DL, Barnidge DR, Ladwig PM, Snyder MR. Quantitation of infliximab using clonotypic peptides and selective reaction monitoring by LC-MS/MS. Int Immunopharmacol. Sep 2015;28(1):513-20. doi:10.1016/j.intimp.2015.07.007
11. Willrich MAV, Lazar-Molnar E, Snyder MR, Delgado JC. Comparison of Clinical Laboratory Assays for Measuring Serum Infliximab and Antibodies to Infliximab. J Appl Lab Med. 2018;2(6):893-903. doi:10.1373/jalm.2017.024869
Report Available
3 to 6 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.CPT Code Information
80230
82397-(if appropriate)
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| INFXR | Infliximab QN with Reflex to Ab, S | 39803-2 |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 63000 | Infliximab, S | 39803-2 |
| 36847 | Interpretation | 59462-2 |
Method Name
INFXR, INFX: Selective Reaction Monitoring Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS)
INXAB: Electrochemiluminescent Bridging Immunoassay with Acid Dissociation
Forms
If not ordering electronically, complete, print, and send 1 of the following with specimen:
-Gastroenterology and Hepatology Test Request (T728)
-Therapeutics Test Request (T831)
-General Request (T239)
Day(s) Performed
Monday through Friday