What it measures
The red blood cell count is the number of red cells in a litre of blood. Red cells carry oxygen around the body. It is part of a full blood count and is given in millions of millions per litre (×10¹²/L).
Why people test it
- Part of a full blood count, used with haemoglobin to check for anaemia.
- Measured to look for too many red cells, which makes the blood thicker.
- A high count with small red cells can point to an inherited trait such as thalassaemia, so it is read with MCV.
- Testosterone therapy can raise the red cell count, so it is watched on TRT alongside haematocrit.
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 4.50 to 6.50 ×10¹²/L for adult men and 3.80 to 5.80 ×10¹²/L for adult women. 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.