Intrinsic Factor Blocking Antibody, Serum
Use
This test is useful for confirming the diagnosis of pernicious anemia. A positive result for intrinsic factor blocking antibody (IFBA) strongly supports a diagnosis of pernicious anemia (PA). Since the diagnostic sensitivity of IFBA testing for PA is only around 50%, an indeterminate or negative IFBA test does not exclude the diagnosis of PA. Measurement of serum gastrin levels will help in these cases, as fasting serum gastrin is elevated in PA. Most patients with PA have autoantibodies against gastric parietal cells or IF; the latter is very specific but present in only 50% of cases.
Special Instructions
Patients should fast for at least 8 hours before specimen collection. This test should not be performed on patients who have received a vitamin B12 injection or radiolabeled vitamin B12 within the previous 2 weeks. The test uses a competitive binding immunoenzymatic assay method.
Limitations
Patients with other autoimmune diseases may have positive IFBA assays without having PA. During validation, 5 of 15 patients with rheumatoid arthritis were IFBA positive. The test may interfere in patients who have received vitamin B12 injections within the last 2 weeks, possibly leading to false results. Heterophile antibody interference risk is low due to the competitive binding nature of this assay.
FDA ApprovedNew York Approved
Methodology
Immunoassay (Immunoenzymatic Assay)
Biomarkers
LOINC Codes
- 31444-3
- 31444-3
- 48767-8
Result Turnaround Time
1-3 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.5 mL
Container
Plastic vial
Collection Instructions
Centrifuge and aliquot serum into a plastic vial.
Patient Preparation
Fasting: 8 hours, required. This test should not be performed on patients who have received a vitamin B12 injection or radiolabeled injection within the previous 2 weeks.
Causes for Rejection
Gross hemolysis
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 14 days |
| Frozen | 14 days |