A full blood count has three main components:
Here is more information on these three components.
For adults, normal Hb levels are:
Note. So a Hb of 120 g/L is anaemia for a man, but not a woman.
The Hb reflects the number of red cells (which carry oxygen) in the blood – a higher number means more red cells. A low haemoglobin is called anaemia. A high haemoglobin is called polycythaemia.
For adults, a normal white count is 4-11 x10^9/L (million per litre)
These cells fight infection (and cancer and foreign bodies inside you). If you have too many of them, it could be a sign of inflammation, infection, cancer or another medical condition. If it’s low, you could be at a higher risk for infection. A medication, a viral infection, or a bone marrow disease could also cause a low count.
For adults, a normal platelet count is 150-400 x10^9/L (million per litre).
These cells clot the blood.
Note. Different laboratories/hospitals will have slightly different normal ranges.