MCV, or mean corpuscular volume, measures the average volume or size of individual red blood cells (RBCs). An elevated MCV indicates that the RBCs are larger than normal, a condition referred to as macrocytosis. Several factors can cause an elevated MCV.
Below is a list in approximate order of prevalence in a general Western population, particularly focusing on countries like Australia, the US, or the UK:
- Alcohol Use: Chronic alcoholism is a common cause of macrocytosis.
- Vitamin Deficiencies:
- Folate deficiency: Less common after the fortification of grains in some countries.
- Vitamin B12 deficiency: Often due to dietary insufficiencies in the elderly or vegetarians, or malabsorption conditions.
- Medications: Drugs like methotrexate, antiretroviral agents, and certain anticonvulsants (phenytoin, valproate, carbamazepine) can elevate MCV.
- Liver Disease: Liver disorders, especially cirrhosis, can be a frequent cause given the prevalence of conditions like alcoholic liver disease and non-alcoholic fatty liver disease.
- Hypothyroidism: Thyroid disorders are relatively common, especially among older women.
- Bone Marrow Disorders: These are less common than the above causes.
- Myelodysplastic syndromes (MDS)
- Aplastic anemia
- Acute myeloid leukemia
- Reticulocytosis: The prevalence varies based on the underlying cause, whether it’s hemolytic anemia, recent blood loss, etc.
- Smoking: Chronic smoking can lead to a mildly elevated MCV.
- Miscellaneous Causes: Rare conditions like congenital membrane defects or enzyme deficiencies.