Macrocytic anaemia

Principal causes of macrocytic anaemia are:

Vitamin B12 deficiency

• Pernicious anaemia. Check for atrophic gastritis, resulting in a lack of intrinsic factor due to anti-parietal cell antibodies.

• Stomach surgery in the medical history (deficiency of intrinsic factor)

• Secondarily to poor nutrition (for example in veganism)

• Diphyllobothrium latum tapeworm (rare)

• Chronic ileitis (Crohn, tuberculosis) / ileal resection (disturbed vitamin B12 absorption)

• Bacterial overgrowth in the small intestine such as in blind loop syndrome, multiple small intestine diverticulae and sclerodermia.

• There are rare genetic abnormalities, such as transcobalamine deficiency, which can result in macrocytic / megaloblastic anemia.

Folic acid deficiency

• Deficient nutrition

• Increased requirements: pregnancy, chronic haemolysis.

• Seldom due to medication, e.g. folic acid antagonists (pyrimethamine, trimethoprim), sulphasalazine, phenytoin (diphenylhydantoin)

• Malabsorption : gluten enteropathy, tropical sprue

Category: Pathology Notes