From the Guidelines
An elevated Mean Corpuscular Volume (MCV) indicates macrocytosis, which is often caused by vitamin B12 or folate deficiency, and the first step in management should be to identify and treat the underlying cause, with supplementation of vitamin B12 or folate being a common approach, as indicated by the European Consensus on the diagnosis and management of iron deficiency and anaemia in inflammatory bowel diseases 1. To address this finding, the following steps can be taken:
- Identify the underlying cause of the macrocytosis, which may include vitamin B12 or folate deficiency, alcoholism, liver disease, hypothyroidism, or certain medications.
- Supplement with oral vitamin B12 1000 mcg daily or intramuscular injections (1000 mcg weekly for 4 weeks, then monthly) for B12 deficiency, as this is a common cause of macrocytosis 1.
- Take 1 mg daily orally for folate deficiency, as this is another common cause of macrocytosis.
- Abstinence from alcohol is crucial if the macrocytosis is alcohol-related.
- Medication-induced macrocytosis may require adjusting or changing medications when possible. Further testing should include:
- A complete blood count with peripheral smear to evaluate the red blood cells.
- Vitamin B12 and folate levels to assess for deficiencies.
- Liver function tests to evaluate for liver disease.
- Thyroid function tests to evaluate for hypothyroidism.
- Reticulocyte count to assess bone marrow function. It is essential to note that macrocytosis without anemia may be monitored if mild, while severe cases or those with neurological symptoms require prompt treatment, as indicated by the clinical practice guidelines for evaluation of anemia 1. The elevated MCV reflects impaired DNA synthesis affecting cell division, resulting in larger but fewer red blood cells with normal hemoglobin content.
From the Research
Elevated MCV
- Elevated Mean Corpuscular Volume (MCV) is associated with various conditions, including aging, nutrition, alcohol abuse, and certain diseases 2.
- Chronic alcohol consumption can lead to malnutrition and deficiency of essential vitamins, including folate, which can cause elevated MCV 3, 4.
- Studies have shown that alcoholics may have increased MCV levels, even in the absence of folate deficiency 3, 5.
- Elevated MCV levels have been linked to an increased risk of all-cause mortality, cancer mortality, and liver cancer mortality in non-anemic individuals 2.
- Macrocytic anemias, characterized by an MCV >100 fL, can be classified into megaloblastic or nonmegaloblastic anemia, with different underlying causes and treatment approaches 6.
Causes of Elevated MCV
- Alcohol abuse and malnutrition can lead to folate deficiency, causing elevated MCV 3, 4.
- Other causes of macrocytic anemia include vitamin B12 deficiency, myelodysplastic syndrome, liver dysfunction, hypothyroidism, and certain drugs 6.
- Iron metabolism disturbances, including iron overload or deficiency, can also occur in patients with alcohol dependence, but may not be directly related to elevated MCV 5.