Pernicious anemia is a type of large cell, or macrocytic, anemia. It’s sometimes called megaloblastic anemia because of the abnormally large size of the red blood cells produced.
Pernicious anemia is not the only kind of macrocytic anemia. Other causes of abnormally large red blood cells include:
the long-term use of certain medications and antibiotics, such as methotrexate and azathioprine
chronic obstructive pulmonary disease
chronic alcoholism
folate (vitamin B-9) deficiency caused by poor diet or disorders that affect absorption
Other causes of vitamin B-12 deficiency, such as poor diet, are often confused with pernicious anemia. Pernicious anemia is strictly an autoimmune disorder resulting from a lack of IF. Pernicious anemia is also seen in children who are born with a genetic defect that prevents them from making IF.