What it measures
MCV (mean cell volume) is the average size of your red blood cells. The analyser measures it as part of a full blood count, and it is given in femtolitres (fL).
Why people test it
- Helps tell types of anaemia apart, as red cells tend to be small when iron is low.
- Red cells tend to be large when B12 or folate is low, so MCV is read with those tests.
- Can also rise with regular heavy drinking, an underactive thyroid and some medicines.
Typical range
Ranges vary between labs, with the method used, age and sex, and your report shows the lab's own range. One NHS trust lab gives 80 to 100 fL for adults. Source: Gloucestershire Hospitals NHS Foundation Trust: haematology reference ranges.
Finger-prick or vein?
A vein draw is usually advised. Finger-prick samples can clot or have their red cells burst (haemolyse) in the tube, which upsets blood count results.