Pernicious anaemia (also known as Biermer’s disease) is an autoimmune atrophic gastritis, predominantly of the fundus, and is responsible for a deficiency in vitamin B12 (cobalamin) due to its malabsorption. Its prevalence is 0.1% in the general population and 1.9% in subjects over the age of 60 years. Pernicious anaemia represents 20%–50% of the causes of vitamin B12 deficiency in adults. Anti intrinsic factor antibodies do not appear to have a clearly defi ned pathogenic role in the development of gastritis. By contrast, they have a well-documented role in the onset of pernicious anaemia, via the vitamin B12 deficiency they induce. The finding of a low total serum cobalamin level may be further evaluated by testing for anti-intrinsic factor antibodies. If positive, the antibodies have a high positive predictive value (95%) for the presence of pernicious anaemia with a concurrent low false positive rate (1–2%) i.e. a high specificity. It identifies those patients with a need for lifelong cobalamin replacement therapy.2 With regard to diagnostic performance sensitivity is low for anti-intrinsic factor antibodies, in the most recent studies while specificity is 100%. In combination with anti-parietal cell antibodies they yield 73% sensitivity and 100% specificity.
Preparation of Patient: No special preparation.