Biomarker · Blood cells

Mean corpuscular volume (MCV)

Also known as: MCV, mean cell volume, red cell size

The average size of a red blood cell, calculated by the analyser during a full blood count. Small cells (microcytosis) point towards iron deficiency, large cells (macrocytosis) towards B12 or folate deficiency, alcohol or liver disease.

Open in the 3D explorerSpleen anatomy
3D model of the Spleen in the Anatomy Nexus anatomy atlas
Interactive 3D model: Spleen. Orbit, zoom and click the structures.Load the 3D model
Also known as
MCV, mean cell volume, red cell size
Units
fL (femtolitres)
Measured by
Full blood count

What it is and what it does

Red cells are normally about 80 to 100 femtolitres in volume. When haemoglobin production is limited by iron shortage or a thalassaemia trait, the marrow releases smaller, paler cells. When DNA synthesis is slowed by lack of vitamin B12 or folate, or by alcohol, some drugs or liver disease, cells are released larger than normal. The MCV is therefore the first branch point in working out why someone is anaemic, alongside the red cell distribution width (RDW), which measures how variable the sizes are.

Why it may be higher

  • Vitamin B12 or folate deficiency
  • Alcohol excess and liver disease
  • Hypothyroidism
  • Some medicines (for example hydroxycarbamide, methotrexate, some antiretrovirals)
  • Reticulocytosis after bleeding or haemolysis (young red cells are large)
  • Myelodysplasia

Why it may be lower

  • Iron deficiency
  • Thalassaemia trait and other inherited haemoglobin disorders
  • Long-standing inflammatory disease (anaemia of chronic disease, sometimes)
  • Lead poisoning (rare)

A high or low value can be associated with several different situations. The result is interpreted with other results, symptoms, history and clinical findings.

What can affect the result

  • A mixed deficiency (iron and B12) can leave the MCV normal
  • Recent transfusion
  • Very high white-cell counts or cold agglutinins can distort analyser readings
Reference ranges. Reference intervals for this marker depend on the laboratory, the assay, the units, age, sex and pregnancy. Interpret a result against the interval printed on the laboratory report, not against a figure from the internet.

Medicines that can change it

MetforminOmeprazole

Each medicine page lists its effect on this marker under "Effects on tests and results", with the source.

Educational content. A biomarker page explains what a substance is and why its level can change. It cannot determine the cause of your result: interpret a result using the range supplied by the laboratory that performed the test, with the clinician who ordered it.