Finding the right tests…
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Finding the right tests…
Haematology
A haemoglobin test measures how much of this oxygen-carrying protein is packed into your red blood cells. It is one of the most frequently ordered blood tests because so many common conditions - blood loss, iron deficiency, chronic kidney disease, pregnancy - show up first as a change in this one number. Adult men typically run higher than adult women, and newborns run higher still, so results are always read against an age- and sex-matched range rather than a single universal cutoff. It is almost always drawn as part of a full blood count rather than requested by itself, and needs no special preparation beforehand for most adults.
The result is reported in grams per decilitre (g/dL) of blood. Typical adult reference ranges run about 13.8 to 17.2 g/dL for men and 12.1 to 15.1 g/dL for women, with separate ranges for newborns and infants, who run higher and lower respectively at different stages. It is measured from the same blood draw used for a complete blood count, alongside red cell count and volume, so the three numbers are usually read together rather than in isolation.
Low haemoglobin, or anaemia, can come from blood loss, a shortage of iron, vitamin B12 or folate, kidney disease that slows red cell production, or the marrow simply not producing enough cells. High haemoglobin is less common and usually points toward long-term low oxygen levels, dehydration, or occasionally a bone marrow condition that overproduces red cells.
A low reading confirms anaemia but not its cause. Iron studies, vitamin levels or a peripheral smear are usually needed next to work out why the number is low, especially if it is found unexpectedly.
- Fatigue, breathlessness or unusual paleness - Heavy menstrual periods or any unexplained bleeding - Routine pregnancy check-ups - Monitoring a known chronic illness such as kidney disease - A general annual health check-up
Because haemoglobin can shift with hydration, altitude and recent blood loss, a single reading taken in isolation is sometimes repeated before your doctor draws conclusions from it. Ask your doctor how your result compares with your previous readings, if you have them.
Typical adult reference ranges are about 13.8 to 17.2 g/dL for men and 12.1 to 15.1 g/dL for women, with different ranges for children and newborns. Ranges vary by lab, so check the one printed on your own report.
It usually points to anaemia, which can have several causes - blood loss, iron or vitamin deficiency, chronic illness or a bone marrow problem. Further tests are often needed to work out the specific cause.
Yes. Dehydration can concentrate your blood and make haemoglobin look higher than it really is, while being well hydrated can do the opposite. Your doctor takes this into account when reviewing a borderline result.
No special preparation is usually required. Ask your doctor or the centre if other tests are being drawn during the same visit, since one of those might need fasting.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
No. Haemoglobin measures the oxygen-carrying protein in your red blood cells, while iron studies measure iron stored and circulating in your body. Low iron is one common cause of low haemoglobin, but they are separate tests.
Red cell production and blood volume differ by sex, age and hormonal stage. That's why laboratories use separate reference ranges for adult men, adult women, infants and newborns.