From the Guidelines
Macrocytic hyperchromic anemia is primarily caused by vitamin B12 or folate deficiency, and treatment should focus on addressing the underlying cause, with vitamin B12 deficiency being a critical condition that can lead to irreversible neurological damage if left untreated. The condition is characterized by abnormally large red blood cells (macrocytosis) with increased hemoglobin concentration (hyperchromia). According to the most recent guidelines, vitamin B12 absorption is adversely affected by certain surgical procedures, and deficiency may present several years after surgery 1.
Causes and Diagnosis
The most common causes of macrocytic hyperchromic anemia include:
- Vitamin B12 deficiency
- Folate deficiency
- Alcoholism
- Liver disease
- Certain medications Diagnosis is made through blood tests showing elevated mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) 1.
Treatment
Treatment depends on identifying and addressing the underlying cause. For B12 deficiency, intramuscular cyanocobalamin injections are typically given at 1000 mcg daily for one week, then weekly for one month, followed by monthly maintenance doses. For folate deficiency, oral folic acid supplementation at 1-5 mg daily is recommended 1. Patients with alcohol-related anemia should abstain from alcohol and receive nutritional support including B vitamins.
Laboratory Evaluation
Laboratory evaluation should include:
- Complete blood count with peripheral smear
- Reticulocyte count
- Vitamin B12 and folate levels
- Liver function tests
- Thyroid studies Patients may experience symptoms such as fatigue, weakness, shortness of breath, and neurological symptoms (particularly with B12 deficiency) 1. Prompt treatment is essential to prevent complications, especially neurological damage in cases of B12 deficiency which can become irreversible if left untreated.
From the FDA Drug Label
CLINICAL PHARMACOLOGY Folic acid acts on megaloblastic bone marrow to produce a normoblastic marrow. In man, an exogenous source of folate is required for nucleoprotein synthesis and the maintenance of normal erythropoiesis Folic acid is a precursor of tetrahydrofolic acid, which is involved as a cofactor for transformylation reactions in the biosynthesis of purines and thymidylates of nucleic acids Impairment of thymidylate synthesis in patients with folic acid deficiency is thought to account for the defective deoxyribonucleic acid (DNA) synthesis that leads to megaloblast formation and megaloblastic and macrocytic anemias. INDICATIONS AND USAGE Folic acid is effective in the treatment of megaloblastic anemias due to a deficiency of folic acid (as may be seen in tropical or nontropical sprue) and in anemias of nutritional origin, pregnancy, infancy, or childhood.
Macrocytic hyperchromic anemia is related to megaloblastic and macrocytic anemias caused by folic acid deficiency. The treatment for this condition is folic acid supplementation 2 2.
- Folic acid is effective in treating megaloblastic anemias due to folic acid deficiency.
- Folic acid deficiency can lead to macrocytic anemia. The use of folic acid can help to produce a normoblastic marrow and maintain normal erythropoiesis.
From the Research
Definition and Classification of Macrocytic Hyperchromic Anemia
- Macrocytic anemia is defined as a red blood cell (RBC) mean corpuscular volume (MCV) >100 femtoliter (fL) 3
- It is generally classified into megaloblastic or nonmegaloblastic anemia 3, 4
- Megaloblastic anemia is caused by deficiency or impaired utilization of vitamin B12 and/or folate 3, 4
- Nonmegaloblastic macrocytic anemia is caused by various diseases such as myelodysplastic syndrome (MDS), liver dysfunction, alcoholism, hypothyroidism, certain drugs, and less commonly inherited disorders of DNA synthesis 3, 4, 5
Causes of Macrocytic Hyperchromic Anemia
- Vitamin B12 deficiency is the most common cause for megaloblastic anemia 6, 4
- Folate deficiency also can contribute to megaloblastic anemia 6, 4
- Other causes of macrocytic anemia include chronic liver dysfunction, hypothyroidism, alcohol use disorder, and myelodysplastic disorders 4, 5
- Macrocytosis also can result from release of reticulocytes in the normal physiologic response to acute anemia 4
Diagnosis and Evaluation of Macrocytic Hyperchromic Anemia
- A carefully obtained history and examination with evaluation of a peripheral blood smear and reticulocyte count should be performed in most patients with macrocytosis 5
- Serum vitamin B12 and folate levels, serum thyroid studies, liver function studies, and bone marrow aspirate and biopsy with cytogenetic analysis are frequently required to confirm a diagnosis suspected on the basis of the initial evaluation 5
- Macrocytic megaloblastic anemia is the most typical but the latest sign of a cobalamin (vitamin B12) and/or folic acid deficiency or of a congenital abnormality of cobalamin and folate metabolism 7