From the Guidelines
The patient's lab results indicate macrocytosis, suggesting possible vitamin B12 or folate deficiency, which should be evaluated with specific testing for these nutrients, as indicated by the European Consensus on the Diagnosis and Management of Iron Deficiency and Anaemia in Inflammatory Bowel Diseases 1. The findings of an elevated MCV of 101.7 fL and slightly elevated MCH of 33.3 pg in a 74-year-old patient with coronary artery disease (CAD) are notable. According to the 2019 ESC Guidelines for the Diagnosis and Management of Chronic Coronary Syndromes 2, a full blood count, including hemoglobin, is recommended in all patients with suspected CAD. Given the patient's age and CAD history, these abnormalities warrant follow-up testing, including:
- B12 and folate levels to assess for nutritional deficiencies
- TSH to evaluate thyroid function, as recommended in cases of clinical suspicion of thyroid disorders 2
- Liver function tests to assess for any underlying liver disease Other causes to consider include alcohol use, medication effects, or reticulocytosis, as mentioned in the European Consensus on the Diagnosis and Management of Iron Deficiency and Anaemia in Inflammatory Bowel Diseases 1. The other blood count parameters (white blood cells, red blood cells, hemoglobin, hematocrit, and MCHC) are within normal limits. While these mild abnormalities don't require immediate intervention, they should be addressed during the next clinical visit to identify and treat any underlying causes, especially since nutritional deficiencies can impact cardiovascular health in elderly patients with CAD.
From the Research
Laboratory Results
- The patient's white blood cell count is 5.4 thousand/uL, which is within the normal range of 3.8-10.8 thousand/uL 3, 4, 5.
- The red blood cell count is 4.20 million/uL, which is within the normal range of 4.20-5.80 million/uL.
- The hemoglobin level is 14.0 g/dL, which is within the normal range of 13.2-17.1 g/dL.
- The hematocrit is 42.7%, which is within the normal range of 38.5-50.0%.
- The mean corpuscular volume (MCV) is 101.7 fL, which is higher than the normal range of 80.0-100.0 fL, indicating macrocytosis 3, 4, 5, 6.
- The mean corpuscular hemoglobin (MCH) is 33.3 pg, which is higher than the normal range of 27.0-33.0 pg.
- The mean corpuscular hemoglobin concentration (MCHC) is 32.8 g/dL, which is within the normal range of 32.0-36.0 g/dL.
Macrocytosis
- Macrocytosis is defined as a red blood cell mean corpuscular volume (MCV) >100 femtoliter (fL) 3, 4, 5.
- The patient's MCV is 101.7 fL, which indicates macrocytosis.
- Macrocytic anemias are generally classified into megaloblastic or nonmegaloblastic anemia 3, 4, 5.
- Megaloblastic anemia is caused by deficiency or impaired utilization of vitamin B12 and/or folate, whereas nonmegaloblastic macrocytic anemia is caused by various diseases such as myelodysplastic syndrome (MDS), liver dysfunction, alcoholism, hypothyroidism, certain drugs, and by less commonly inherited disorders of DNA synthesis 3, 4, 5.
Differential Diagnosis
- The patient's macrocytosis could be caused by megaloblastic anemia, nonmegaloblastic macrocytic anemia, or other conditions such as reticulocytosis 4, 6.
- Further testing, such as vitamin B12 and red blood cell folate levels, reticulocyte count, and thyroid and liver function tests, may be necessary to determine the underlying cause of the patient's macrocytosis 4, 6.
- A blood smear should be performed to differentiate between megaloblastic and nonmegaloblastic anemia 4.
- The patient's age (74 years) and history of CAD may also be relevant in determining the underlying cause of the macrocytosis 3, 7.