From the Guidelines
The patient's macrocytic anemia, as indicated by the high MCV (104.5) and high MCH (35.1), should be further evaluated with vitamin B12 and folate levels, liver function tests, and a detailed medication review, as these are the most common causes of this type of anemia 1. The blood test results for this 67-year-old male show mild anemia with low red blood cell count (3.36), low hemoglobin (11.8), and low hematocrit (35.1). This appears to be a macrocytic anemia, as indicated by the high MCV (104.5) and high MCH (35.1). Some key points to consider in the evaluation of this patient's anemia include:
- The morphologic approach to evaluating anemia, which characterizes anemia based on the mean corpuscular volume (MCV), or average RBC size, reported in the initial CBC test 1
- The kinetic approach, which focuses on the underlying mechanism of anemia, distinguishing among the production, destruction, and loss of RBCs, and uses the reticulocyte count corrected against the degree of anemia (reticulocyte index [RI]) as a measurement of the fraction of reticulocytes (immature RBCs) 1
- The patient's normal RDW (12.7) and normal platelet count (145) suggest that the anemia is not due to a bone marrow disorder or a bleeding disorder
- The patient's normal white blood cell count, differential, and absolute neutrophil and lymphocyte counts suggest that there is no underlying infection or inflammatory process that could be contributing to the anemia While waiting for these additional tests, the patient should increase dietary intake of B12 and folate-rich foods (eggs, meat, leafy greens) or begin supplementation with vitamin B12 (1000 mcg daily) and folate (1 mg daily) after discussing with their physician. Some potential causes of macrocytic anemia that should be considered in this patient include:
- Vitamin B12 deficiency, which can be diagnosed with a low vitamin B12 level 1
- Folate deficiency, which can be diagnosed with a low folate level 1
- Liver disease, which can be diagnosed with abnormal liver function tests 1
- Alcoholism, which can be diagnosed with a detailed social and medical history 1
- Certain medications, which can be diagnosed with a detailed medication review 1
From the FDA Drug Label
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 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. The patient has low hemoglobin, low hematocrit, high MCV, and high MCH, which are indicative of macrocytic anemia.
- The patient's MCV is 104.5, which is high, and the MCH is 35.1, which is also high.
- The patient's red blood cell count is 3.36, which is low. The patient's laboratory results suggest macrocytic anemia, which can be caused by folic acid deficiency 2.
From the Research
Blood Test Results Analysis
The provided blood test results show:
- Low red blood cell count (3.36)
- Low hemoglobin (11.8)
- Low hematocrit (35.1)
- High MCV (104.5)
- High MCH (35.1)
- Normal MCHC (33.6)
- Normal RDW (12.7)
Possible Causes of Macrocytic Anemia
The high MCV value indicates macrocytic anemia, which can be caused by:
- Vitamin B12 deficiency 3, 4, 5, 6, 7
- Folate deficiency 3, 4, 5, 6, 7
- Myelodysplastic syndrome (MDS) 3
- Liver dysfunction 3
- Alcoholism 3
- Hypothyroidism 3
- Certain drugs 3
- Inherited disorders of DNA synthesis 3
Association with Vitamin B12 and Folate Deficiency
Studies have shown that low vitamin B12 and folate levels are associated with anemia and macrocytosis 5, 6, 7. Additionally, high homocysteine levels are often seen in patients with vitamin B12 and folate deficiency 6.
Diagnostic Considerations
To diagnose the underlying cause of macrocytic anemia, further testing may be necessary, including: