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Intrinsic Factor Blocking Antibody, Serum

Reporting Name

Intrinsic Factor Blocking Ab, S
Seattle Children's Hospital Note:

Clinical System Name: Miscellaneous Test

Useful For

Confirming the diagnosis of pernicious anemia

Specimen Required


Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 1 mL

Additional Information: This test should not be ordered on patients who have received vitamin B12 injection within the last 2 weeks.

Specimen Type


Specimen Minimum Volume

0.5 mL

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 14 days
  Frozen  14 days

Day(s) and Time(s) Performed

Monday through Friday; 5 a.m.-12 p.m., Saturday; 6 a.m.-6 p.m.

Performing Laboratory

Mayo Medical Laboratories in Rochester

Method Name

Immunoenzymatic Assay

Method Description

The instrument used is a Beckman Coulter Unicel DXI 800. The Access Intrinsic Factor Antibody assay is a competitive binding immunoenzymatic assay. A sample is added to a reaction vessel along with intrinsic factor alkaline phosphatase conjugate and a protein blocking solution. Intrinsic factor antibody in the sample binds to the intrinsic factor conjugate. After incubation in a reaction vessel, paramagnetic particles coated with a mouse monoclonal, specific for the vitamin B12 binding site on intrinsic factor, is added to the reaction. Intrinsic factor conjugate that has not been blocked by sample anti-intrinsic factor binds to the monoclonal antibody on the solid phase. After an additional incubation in the reaction vessel, materials bound to the solid phase are held in a magnetic field, while unbound materials are washed away. Chemiluminescent substrate is added to the vessel and light generated by the reaction is measured with a luminometer. The light production is inversely proportional to the concentration of intrinsic factor antibody in the sample expressed in AU/mL (Antibody Units/mL). The amount of analyte in the sample is determined from a stored calibration.(Beckman Coulter Assay Manual 2009, Beckman Coulter Inc., Fullerton, CA)

Reference Values


Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information


LOINC Code Information

Test ID Test Order Name Order LOINC Value
IFBA Intrinsic Factor Blocking Ab, S 31444-3


Result ID Test Result Name Result LOINC Value
IFBLA Intrinsic Factor Blocking Ab, S 31444-3
CMT31 Comment 48767-8

Testing Algorithm

See Vitamin B12 Deficiency Evaluation in Special Instructions.

Reject Due To


Mild OK; Gross reject


Mild OK; Gross OK





Special Instructions