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Test Code INFXP Infliximab Quantitation with Antibodies to Infliximab, Serum

Additional Codes

Internal / External / Beaker: LAB5555


Specimen Required


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

Supplies: Sarstedt Aliquot Tube, 5 mL (T914)

Collection Container/Tube:

Preferred: Red top

Acceptable: Serum gel

Submission Container/Tube: Plastic vial

Specimen Volume: 1.2 mL Serum

Collection Instructions:

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

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


Secondary ID

620151

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

 

These assays do not differentiate between the originator and biosimilar products.

Profile Information

Test ID Reporting Name Available Separately Always Performed
INFX Infliximab, S Yes, (INFXR) Yes
INXAB Infliximab Ab, S No Yes

Testing Algorithm

When this test is ordered, infliximab quantitation and testing for antibodies to infliximab will always be performed.

 

For more information see Ulcerative Colitis and Crohn Disease Therapeutic Drug Monitoring Algorithm.

Method Name

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

INXAB: Electrochemiluminescent Bridging Immunoassay with Acid Dissociation

Reporting Name

Infliximab QN with Antibodies, S

Specimen Type

Serum Red

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
Heat-Treated 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

Day(s) Performed

INFX: Monday through Friday

INXAB: Monday, Wednesday, Friday

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

INFX-80230

INXA -82397

LOINC Code Information

Test ID Test Order Name Order LOINC Value
INFXP Infliximab QN with Antibodies, S 103791-0

 

Result ID Test Result Name Result LOINC Value
63417 Infliximab Ab, S 72623-2
63000 Infliximab, S 39803-2
36847 Interpretation 59462-2
36654 INXAB Interpretation 59462-2

Forms

If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Test Request (T728) with the specimen.