Assay

Intrinsic factor antibodies

Key Words

Intrinsic factor antibodies, IFA

 Specimen Collection

Serum (brown)

Turnaround time

28 days

Test indications

The combination of intrinsic factor antibody positivity and low vitamin B₁₂ is diagnostic of Pernicious Anaemia. However a negative test for serum antibodies against intrinsic factor does not exclude pernicious anaemia as this test is insensitive, with only approximately 50% of patients with pernicious anaemia having intrinsic factor antibodies. For this reason, gastric parietal cell antibodies are used to screen for pernicious anaemia, and intrinsic factor antibodies are used as a confirmatory test accepting that not all patients with pernicious anaemia will have intrinsic factor antibodies. Only GPC-positive samples will be tested for intrinsic factor antibodies.

Methodology

Enzyme Immunoassay

Interferences

No known methodological interferences

Reference Range

Negative:   <7 EliA U/mL

Equivocal:  7-10 ELiA U/mL

Positive:    >10 ELiA U/mL

Analytical error

Contact laboratory (x8454)

Reference change value

N/A