From the Guidelines
Increased Mean Corpuscular Volume (MCV) is primarily caused by vitamin B12 or folate deficiency, alcoholism, liver disease, and certain medications, as supported by the most recent evidence from 2019 1. The causes of increased MCV can be categorized into several groups, including:
- Vitamin B12 or folate deficiency, which impairs red blood cell maturation, resulting in larger cells
- Alcoholism, which directly damages red blood cell membranes and interferes with folate metabolism
- Liver disease, which affects red blood cell production due to impaired protein synthesis
- Certain medications, such as anticonvulsants (phenytoin, valproic acid), chemotherapy agents (methotrexate, hydroxyurea), and antiretrovirals (zidovudine) Other causes of increased MCV include:
- Hypothyroidism
- Myelodysplastic syndromes
- Reticulocytosis
- Hereditary conditions like Diamond-Blackfan anemia When evaluating increased MCV, it's essential to check:
- Vitamin B12 and folate levels
- Liver function tests
- Thyroid function
- Medication history Treatment should target the underlying cause, such as:
- Vitamin supplementation for deficiencies (B12 1000 mcg daily or folate 1-5 mg daily) 1
- Alcohol cessation
- Medication adjustment when appropriate It's also important to note that the diagnosis of iron deficiency and anaemia of chronic disease can be complex, and the distinction between these conditions is crucial for appropriate treatment, as highlighted in the 2015 European consensus on the diagnosis and management of iron deficiency and anaemia in inflammatory bowel diseases 1.
From the Research
Causes of Increased MCV
- Increased Mean Corpuscular Volume (MCV) is a condition where the average size of red blood cells is larger than normal, which can be caused by various factors, including:
- Folate deficiency: Studies have shown that folate deficiency is a common finding in patients with alcohol use disorder, and macrocytosis (MCV>100fL) is significantly associated with serum folate deficiency 2.
- Vitamin B12 deficiency: Functional vitamin B12 deficiency can occur in alcoholics, even with normal serum cobalamin levels, and may respond to vitamin B12 treatment 3.
- Alcohol-related liver disease: Alcohol-related liver disease (ARLD) has been associated with macrocytosis and folate deficiency 2, 4.
- Malnutrition: Chronic alcohol abuse can lead to malnutrition, resulting in deficiencies of essential nutrients, including folate and vitamin B12 5.
- Other factors that may contribute to increased MCV include:
- Homocysteine metabolism disturbances: Elevated homocysteine levels have been linked to folate and vitamin B12 deficiencies, and may increase the risk of cardiovascular diseases 5.
- Intestinal malabsorption: Chronic alcohol consumption can lead to intestinal malabsorption of folate and other nutrients, contributing to deficiencies 5.