Intrinsic Factor Antibody (IFAB)

Patient Preparation

None

Notes

Antibodies against intrinsic factor (IFA) are seen in 50-70% of patients with pernicious anaemia (PA) . Gastric parietal cell antibodies are considered an appropriated screening test for pernicious anaemia and intrinsic factor antibodies are ideally used to confirm if a GPC has been masked by another antibody (for example anti-mitochondrial antibodies) . There are two types of intrinsic factor antibody that can be detected; type I that block the binding of B12 to intrinsic factor and type II that block the uptake of the intrinsic factor-B12 complex. PA is caused by chronic atrophic gastritis and subsequent reduced absorption of vitamin B12 in the ileum. This results in megaloblastic anaemia and often neurological disorders

Reference Range

Negative <= 20

Equivocal = 20.1- 24.9

Positive >=25.0

A specimen with equivocal levels of Intrinsic Factor antibody cannot be assessed for antibody status. A repeat sample should be taken at a later time.