Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum [A Test in Focus]

The new Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum, test is now available to the Mayo Clinic practice and Mayo Medical Laboratories clients. This test should be ordered to assess a trough level quantitation for evaluation of patients with loss of response to infliximab.


  • Infliximab (Remicade, Janssen Biotech) is a chimeric immunoglobulin (IgG1 kappa) targeting tumor necrosis factor-alpha, and is currently FDA-approved for the treatment of multiple inflammatory conditions.
  • Infliximab is immunogenic and development of an antibody response is associated with loss of response to the drug.
  • Therapeutic concentrations of infliximab may vary according to the disease (eg, Crohn disease vs ulcerative colitis vs rheumatoid arthritis).
  • This test as performed in an algorithmic fashion. Antibody to infliximab testing is performed only if the infliximab result is <5.0 mcg/mL.

How to Use This Test

  • This test should be ordered to assess trough infliximab concentrations to evaluate patients with loss of response to the drug.
  • Trough is the recommended timeframe for infliximab measurement. Infliximab concentrations tend to stabilize after 14 weeks (approximately 100 days). Measurement of peak infliximab concentrations is strongly discouraged.
  • Low trough concentrations indicate lack of response to infliximab. If the trough concentration is <5.0 mcg/mL, testing for antibodies to infliximab will be performed.
  • Based on initial studies, we estimate that approximately 50% of specimens will require antibody testing.
  •  Selective Reaction Monitoring LC-MS/MS
  • Serum Red

Day(s) and Time(s) Test Performed:

  • Monday, Wednesday, Thursday, 4 p.m.

Analytic Time:

  • 3 days
brentwestra (@brentwestra)


Brent Westra is a Marketing Segment Manager at Mayo Clinic Laboratories. He leads marketing strategies for product management and specialty testing along with new media innovations. Brent has worked at Mayo Clinic since 2011.