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HelpTest ID INFXR Infliximab Quantitation with Reflex to Antibodies to Infliximab, Serum
Useful For
Trough level quantitation for evaluation of patients with loss of response to infliximab.
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 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.
Method Name
Selective Reaction Monitoring LC-MS/MS
Reporting Name
Infliximab QN with Reflex to Ab, SSpecimen Type
Serum RedContainer/Tube: Red top
Specimen Volume: 1 mL
Specimen Minimum Volume
0.5 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum Red | Frozen (preferred) | 28 days |
| Refrigerated | 28 days |
Clinical Information
Infliximab (Remicade, Janssen Biotech) is a chimeric immunoglobulin (IgG1 kappa) targeting tumor necrosis factor-alpha (TNF-a), and is currently FDA-approved for the treatment of multiple inflammatory conditions. Infliximab binds to soluble TNF-a and transmembrane homotrimers.
Infliximab pharmacokinetic properties may vary with disease and clearance is affected by concomitant use of immunosuppressants, high concentrations of TNF-a and C-reactive proteins,(1,2) low albumin concentrations, high body mass index, and presence of antibodies-to-infliximab, also known as human antichimeric antibodies (HACA).(3) Males seem to clear infliximab faster than females.(3)
Several studies have demonstrated that infliximab quantitation in the setting of loss of response to therapy can aid in patient management, as trough concentrations defined as therapeutic have been associated with superior clinical response and improved prognosis.(4-6)
Reference Values
Limit of quantitation is 1.0 mcg/mL. Therapeutic ranges are disease specific.
Cautions
Pediatric reference ranges are not established.
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.(3)
Therapeutic concentrations of infliximab may vary according to the disease (eg, Crohn disease vs ulcerative colitis vs rheumatoid arthritis).
Day(s) Performed
Monday, Wednesday, Thursday, 4 p.m.
Report Available
3 daysPerforming Laboratory
Mayo Medical Laboratories in Rochester
Test Classification
This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.CPT Code Information
80299