From the Guidelines
The patient's diagnosis is most likely megaloblastic macrocytic anemia, indicating vitamin B12 or folate deficiency, as evidenced by the elevated MCV, low MCHC, low hematocrit, low hemoglobin, and low RBC count. This diagnosis is based on the morphologic approach to evaluating anemia, which characterizes anemia based on the mean corpuscular volume (MCV) 1. The patient's macrocytic anemia (> 100 fL) suggests a megaloblastic cause, which is most commonly due to vitamin B12 or folate deficiency caused by insufficient uptake or inadequate absorption through lack of intrinsic factor 1.
Key features of the patient's presentation include:
- Elevated MCV (> 100 fL)
- Low MCHC
- Low hematocrit
- Low hemoglobin
- Low RBC count These features are consistent with megaloblastic macrocytic anemia, which is often caused by vitamin B12 or folate deficiency 1.
Initial management should include:
- Vitamin B12 and folate level testing to confirm the diagnosis
- Treatment with vitamin B12 or folate supplements as indicated by the test results
- A complete workup to determine the underlying cause of the deficiency, which may include dietary deficiencies, malabsorption, or other underlying medical conditions
- Follow-up testing to assess response to treatment and adjust the management plan as needed 1.
From the Research
Diagnosis of Macrocytic Anemia
The diagnosis of macrocytic anemia is based on laboratory findings, including an elevated mean corpuscular volume (MCV), low mean corpuscular hemoglobin concentration (MCHC), low hematocrit, low hemoglobin, and low red blood cell (RBC) count 2, 3, 4, 5, 6.
Classification of Macrocytic Anemia
Macrocytic anemias are generally classified into two categories:
- Megaloblastic anemia, caused by deficiency or impaired utilization of vitamin B12 and/or folate 4, 6
- Non-megaloblastic macrocytic anemia, caused by various diseases such as myelodysplastic syndrome (MDS), liver dysfunction, alcoholism, hypothyroidism, certain drugs, and inherited disorders of DNA synthesis 4, 5, 6
Diagnostic Tests
The following tests are commonly used to diagnose macrocytic anemia:
- Vitamin B12 and folate levels 2, 4, 5, 6
- Thyroid function testing 2, 4, 5, 6
- Peripheral blood smear to differentiate between megaloblastic and non-megaloblastic anemia 3, 5, 6
- Reticulocyte count to evaluate bone marrow function 2, 5, 6
- Liver function studies and bone marrow aspirate and biopsy with cytogenetic analysis may be required to confirm a diagnosis 5
Common Causes of Macrocytic Anemia
The most common causes of macrocytic anemia in adults include: