If you have anaemia (too few red blood cells) or polycythaemia (too many red blood cells), to assess its severity, and to monitor response to treatment
As part of a full blood count (FBC), which may be requested for a variety of reasons
A blood sample drawn from a vein in your arm or by a finger-prick (children and adults) or heel-prick (newborns)
This test measures the amount of haemoglobin (a protein found in red blood cells) in your blood and is a good indication of your blood's ability to carry oxygen throughout your body. Haemoglobin carries oxygen to cells from the lungs. If your haemoglobin levels are low, you have anaemia, a condition in which your body is not getting enough oxygen, causing fatigue and weakness.
A blood sample is obtained by inserting a needle into a vein in your arm or by a finger-prick (for children and adults) or heel-prick (for newborns).
No test preparation is needed.
The test is used to:
Haemoglobin measurement is part of the full blood count (FBC) (which is requested for many different reasons) and before operations when a blood transfusion is anticipated. The test is also repeated in patients who have ongoing bleeding problems.
Normal values in an adult male are approximately 135 to 175 grams per litre, and an adult female, 115 to 165 grams per litre of blood but are influenced by the age, sex and ethnic origin of the person. Above-normal haemoglobin levels may be the result of:
Below-normal haemoglobin levels may be the result of:
Haemoglobin decreases slightly during normal pregnancy.
Haemoglobin levels peak around 8 a.m. and are lowest around 8 p.m. each day.
Heavy smokers have higher haemoglobin levels than non-smokers.
Living in high altitudes increases haemoglobin values. This is your body's response to the decreased oxygen available at these heights.
Haemoglobin levels are slightly lower in older men and women and in children.
Full blood count
RCPA ManualBetter Health Channel: Anaemia