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Test Code INFXR Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum

Useful For

Evaluating patients for loss of response, partial response on initiation of therapy, autoimmune or hypersensitivity reactions, primary nonresponse, reintroduction after drug holiday, endoscopic/computed tomography enterography recurrence (in inflammatory bowel disease), acute infusion reactions and proactive monitoring

 

This test does not differentiate between the originator and biosimilar products.

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 quantitation 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, S

Specimen Type

Serum Red


Specimen Required


Patient Preparation:

1. Draw blood immediately before next scheduled dose (trough specimen).

2. For 12 hours before specimen collection, patient should not take multivitamins or dietary supplements (eg, hair, skin, and nail supplements) containing biotin (vitamin B7).

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1 mL Serum

Collection Instructions: Within 2 hours of collection, centrifuge and aliquot serum into plastic vial.


Specimen Minimum Volume

Serum: 0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Red Refrigerated (preferred) 28 days
  Frozen  28 days

Reject Due To

Gross hemolysis Reject
Gross lipemia OK
Gross icterus Reject

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

Report Available

3 to 6 days

Performing 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