Haemoglobin
Also known as: Hb
Related tests: Full blood count
The Test
How is it used?
The test is used to:
- detect and measure the severity of anaemia (too few red blood cells) or polycythaemia (too many red blood cells),
- monitor the response to treatment, and
- help make decisions about blood transfusions.
When is it requested?
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.
What does the test result mean?
Normal values in an adult are approximately 120 to 180 grams per litre (12 to 18 g/dL) of blood but are influenced by the age, sex and ethnic origin in the person. Above-normal haemoglobin levels may be the result of:
- dehydration,
- excess production of red blood cells in the bone marrow,
- severe lung disease, or
- several other conditions.
- iron deficiency
- inherited haemoglobin defects
- bone marrow failure
- cirrhosis of the liver (during which the liver becomes scarred),
- bleeding,
- vitamin and mineral deficiencies,
- kidney disease,
- other chronic illnesses or
- cancers that affect the bone marrow.
Is there anything else I should know?
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.
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