Pernicious Anemia Cascade, Serum
Use
The Pernicious Anemia Cascade test is primarily used for diagnosing pernicious anemia and vitamin B12 deficiency-associated neuropathy. Pernicious anemia is a condition characterized by the deficient production of intrinsic factor by the stomach's parietal cells, leading to impaired vitamin B12 absorption. The cascade of tests provides a comprehensive evaluation for vitamin B12 deficiency by measuring serum vitamin B12 and, if indicated, assessing intrinsic factor blocking antibodies, methylmalonic acid, and serum gastrin levels. These markers help pinpoint the cause of B12 deficiency and guide appropriate treatment strategies.
Special Instructions
Patients must not have received a vitamin B12 injection or radiolabeled vitamin B12 injection within the last two weeks before testing, as these can artificially elevate serum vitamin B12 levels and obscure deficiencies. Additionally, fasting is required, and the patient should avoid taking multivitamins, dietary supplements containing biotin, proton pump inhibitors, and drugs affecting gastrointestinal motility before specimen collection.
Limitations
The test does not detect all cases of vitamin B12 deficiency solely through serum measurements; thus, additional assays like methylmalonic acid and intrinsic factor blocking antibodies may be necessary. Elevated results can occur post vitamin B12 supplementation, and interference from human anti-mouse antibodies can affect results. The presence of other autoimmune diseases may result in positive intrinsic factor blocking antibody tests without true pernicious anemia. Conditions like gastric distention or procedures affecting gastric motility can also lead to skewed gastrin results.
New York Approved
Methodology
Immunoassay (Immunoenzymatic Assay)
Biomarkers
LOINC Codes
- 2132-9
- 2132-9
Result Turnaround Time
1-4 days
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
3 mL
Minimum Volume
1.6 mL
Container
Plastic vial
Collection Instructions
Centrifuge and divide specimen into 3 plastic vials: Vial 1 (B12PA): 1 mL of serum, Vial 2 (PAMMA): 1.5 mL of serum, Vial 3 (PAGAS): 0.5 mL of serum. Band specimens together and send frozen.
Patient Preparation
1. Fasting for 12 hours is required. Avoid multivitamins or dietary supplements containing biotin for 12 hours prior. Do not take proton pump inhibitors for 1 week before specimen collection if feasible. Avoid drugs affecting gastrointestinal motility for 2 weeks before specimen collection.
Storage Instructions
Refrigerated specimens are stable for 24 hours, while frozen specimens are stable for 30 days.
Causes for Rejection
Gross hemolysis, Gross icterus
Stability Requirements
| Temperature | Period |
|---|---|
| Refrigerated | 24 hours |
| Frozen | 30 days |