From the Guidelines
Macrocytic anemia is primarily caused by vitamin B12 and folate deficiency, which are the most common causes of megaloblastic, macrocytic anemia. The most recent and highest quality study, 1, highlights the importance of treating vitamin B12 deficiency immediately, especially in cases with possible neurological involvement. Other causes of macrocytic anemia include alcoholism, liver disease, and certain medications such as methotrexate, phenytoin, and chemotherapy drugs.
Some key points to consider when evaluating macrocytic anemia include:
- Vitamin B12 deficiency can be treated with hydroxocobalamin 1 mg intramuscularly, administered on alternate days until there is no further improvement, then every 2 months 1
- Folate deficiency may indicate non-adherence with daily multivitamin and mineral supplements or malabsorption, and can be treated with oral folic acid 5 mg daily for a minimum of 4 months 1
- Other conditions such as myelodysplastic syndromes, hypothyroidism, and reticulocytosis can also cause macrocytic anemia, as noted in 1 and 1
It is essential to identify and address the underlying cause of macrocytic anemia to provide effective treatment and improve patient outcomes. Treatment should prioritize addressing the underlying cause, such as vitamin B12 injections for B12 deficiency or folate supplementation for folate deficiency.
From the Research
Causes of Macrocytic Anemia
- Megaloblastic anemia, which is caused by deficiency or impaired utilization of vitamin B12 and/or folate 2, 3
- Nonmegaloblastic macrocytic anemia, which is caused by various diseases such as:
- Release of reticulocytes in the normal physiologic response to acute anemia 3