What it measures
Haematocrit is the share of your blood's volume taken up by red blood cells. It is given as a fraction, so 0.45 L/L means red cells make up 45% of the blood. It is part of a full blood count.
Why people test it
- Part of a full blood count, used to check for anaemia, where the figure reads low.
- Measured to look for too many red cells, which makes the blood thicker.
- Dehydration can raise it, so it is read alongside the other blood count results.
- Testosterone therapy can raise haematocrit, so it is monitored regularly on TRT.
- Anabolic steroids can raise it too, and it is often checked during or after a cycle.
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 0.40 to 0.54 L/L for adult men and 0.37 to 0.47 L/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.