Intrinsic Factor Blocking Antibodies
Use
Intrinsic factor is a glycoprotein (produced by the parietal cells of the stomach) that is required for the absorption of vitamin B12 from the diet.1 During digestion, stomach acids dissociate B12 from food and intrinsic factor binds to it and allows it to be absorbed in the small intestine. Conditions that impair intrinsic factor production lead to B12 malabsorption and deficiency. Laboratory findings for B12 deficiency include decreased serum B12 levels, increased methylmalonic acid and megaloblastic anemia.2-6 Impaired hemoglobin synthesis associated with B12 deficiency is characterized by abnormal maturation of erythrocyte precursors in the bone marrow, which results in the presence of megaloblasts with hypersegmented neutrophils and decreased erythrocyte survival.4 Vitamin B12 deficiency is also associated with neurological abnormalities.5,6
Special Instructions
No specimen should be collected from a patient currently undergoing B12 therapy less than one week after the last B12 injection.
Limitations
Anti-intrinsic factor antibodies are less sensitive, being found in only 60% of patients with pernicious anemia, but they are considered highly specific for this condition. Anti-parietal cell antibodies, though present in 90% of PA cases, have low specificity and may appear in other autoimmune conditions without megaloblastic anemia.
Methodology
Immunoassay (CLIA)
Biomarkers
LOINC Codes
- 31443-5
- 31443-5
Result Turnaround Time
2-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
2 mL
Minimum Volume
1 mL
Container
Red-top tube or gel-barrier tube
Collection Instructions
If a red-top tube is used, transfer separated serum to a plastic transport tube.
Patient Preparation
No specimen should be collected from a patient currently undergoing B12 therapy less than one week after the last B12 injection.
Storage Instructions
Refrigerate
Causes for Rejection
Plasma specimen
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 14 days |
| Refrigerated | 14 days |
| Frozen | 14 days |