investigations in pernicious anaemia
Last edited 04/2020 and last reviewed 09/2023
- FBC - macrocytic anaemia, may show neutropaenia and thrombocytopenia
- peripheral blood film shows anisocytosis, poikilocytosis
- low serum vitamin B12; normal folate
- serum bilirubin may be increased because of haemolysis
- bone marrow shows features of megaloblastic erythropoiesis
- detection of autoantibodies:
- parietal cells - serum (95%), gastric juice (70%)
- intrinsic factor - serum (50-60%), gastric juice (85%)
- detection of serum antibodies is usually performed for convenience; only those to IF are diagnostic
- presence of intrinsic factor antibodies in serum
- positive in 50-60% of patients with pernicious anaemia (1)
- the presence of intrinsic factor (IF) is diagnostic of pernicious anaemia but negative intrinsic factor antibodies does not exclude pernicious anaemia (due to the test’s low sensitivity (50-60%)) - gastric parietal cell (GPC) antibodies are seen in 95% of cases of pernicious anaemia and, although there is an overlap with other autoimmune diseases and with normal individuals, a negative result makes pernicious anaemia unlikely (1)
- a positive anti-GPC and/or anti-IF antibody test does need repeating (3)
Other investigations include absorption tests - Schilling test (very rarely undertaken now) - and gastrointestinal investigations.
- Pulse 2004; 64(35):88.
- NHS Wiltshire CCG. Investigation and treatment of Vitamin B12 (cobalamin) deficiency in primary care (accessed 25/4/2020)
- Royal United Hospital Bath NHS Trust. Guidelines for the Investigation & Management of vitamin B12 deficiency (accessed 25/4/2020).
- Mohamed M et al. Pernicious anaemia. BMJ 2020;369:m1319.