Haemoglobin (Hb)

Haemoglobin level, anaemia

Haemoglobin is the protein inside red blood cells that carries oxygen from the lungs to the rest of the body. This test measures how much haemoglobin is in your blood. It is the main test used to find anaemia, a condition in which the blood carries less oxygen than the body needs, and to see how severe it is.

• To check for anaemia if you feel tired, weak, dizzy or short of breath, or look pale
• As a routine check during pregnancy, when anaemia is common
• To follow up heavy periods or other ongoing blood loss
• To monitor treatment for anaemia with iron, vitamin B12 or folate
• Before an operation or as part of a general health check

You do not need to fast, so you can eat and drink as usual. Keep taking your regular medicines, including iron tablets, unless your doctor has told you otherwise. Let the collector know if you bruise easily or take a blood thinner.

Sample

Blood sample

How it works

The collector draws a small blood sample from a vein in your arm at home, and the whole visit takes only a few minutes. The blood goes into a tube that stops it from clotting, so the haemoglobin can be measured accurately at the laboratory.

Report

Within 24 hours of collection.

Your report gives your haemoglobin level next to the laboratory's reference range, which differs for men, women, children and pregnant women. A low level means anaemia, which can be caused by lack of iron, vitamin B12 or folate, blood loss, long-term illness or inherited conditions such as thalassaemia. A high level is less common and can be linked to dehydration, smoking, lung disease or a condition that makes too many red cells. Your doctor will look for the cause and may order more tests.

One test: Haemoglobin (Hb), from one blood sample.