Overview
The mean cell volume (MCV) is a measure of the average volume of a red blood cell.
Assessment of red blood cell size - the presence of normocytosis, microcytosis or macrocytosis - is the first step in the assessment of patients with anaemia as it can rapidly be used to narrow down the likely causes.
Normal Range
- 80-100 fL
Interpretation
- Microcytosis: abnormally small red blood cellsIron deficiency, anaemia of chronic disease, thalassaemia, lead poisoning
- Normocytosis: normally sized red blood cellsAplastic anaemia, acute haemorrhage, haemolysis
- Macrocytosis: abnormally large red blood cellsB12/folate deficiency, alcoholism, myelodysplastic syndrome
Microcytosis
Microcytosis refers to the presence of small red cells with mean corpuscular volume <80 fL.
Causes of Reduced Mean Cell Volume
- Iron deficiency anaemia - nutritional deficiency, blood loss, malabsorption, pregnancy
- Anaemia of chronic disease (chronic infection / inflammation / malignancy)
- Thalassaemia
- Congenital sideroblastic anaemia
- Lead poisoning
- Hyperthyroidism
Macrocytosis
Macrocytosis refers to the presence of large red blood cells with mean corpuscular volume >100 fL.
Macrocytic cells may occur in the context of megaloblastic anaemia, which is typically associated with macroovalocytes (large oval-shaped cells) and hypersegmented neutrophils; they may be seen due to an overabundance of reticulocytes (immature non-nucleated red cells); or may be due to other causes such as liver disease, hypothyroidism or myelodysplastic syndrome.
Causes of Macrocytosis
Megaloblastic
- B12 deficiency
- Folate deficiency
- Scurvy
- Drugs - methotrexate, chemotherapy, reverse transcriptase inhibitors, valproate, phenytoin, nitrous oxide, trimethoprim
Reticulocytosis
- Haemolytic anaemia
- Haemorrhage
- Recovery following bone marrow suppression
Other
- Chronic liver disease
- Chronic alcohol abuse
- Myelodysplastic syndrome
- Post splenectomy
- Aplastic anaemia
- Hypothyroidism
Next Page
----------------------------------------------------------------------------------------------------------------------------------------------------------------------------