Haemoglobin
Haemoglobin is the part of your red blood cells that carries oxygen from your lungs to the rest of your body. A result inside the range on your report usually means your blood is carrying oxygen well. A low result can mean your body isn't getting enough oxygen — doctors call that anaemia — and it is a common, very treatable finding once the cause is known.
Standard Careof Australian adults have an abnormally low haemoglobin level, making anaemia one of the more common findings on a full blood count. Women are more than twice as likely to be affected as men.
What is haemoglobin?
Haemoglobin is an iron-rich protein inside your red blood cells. Its job is to pick up oxygen in your lungs and release it to tissues all over your body. Without enough haemoglobin, your organs and muscles don't get the oxygen they need. Your haemoglobin level is measured in grams per litre (g/L) and is almost always reported as part of a full blood count (FBC) — a single tube of blood that gives your GP a picture of all three main blood cell types: red cells, white cells, and platelets. Because the normal range differs between men and women, the reference interval on your report is sex-specific. When haemoglobin is below the reference range, doctors call this anaemia (from the Greek for "without blood") — a reduction in the blood's oxygen-carrying capacity. Anaemia is a finding, not a diagnosis: the cause still needs to be found. When haemoglobin is above the range, the condition is called polycythaemia (poly = many, cythaemia = blood cells) — an excess of red cells.
Why is it tested?
Haemoglobin testing is ordered when your GP wants to check your blood's oxygen-carrying capacity. The most common reasons are: Persistent tiredness or fatigue, breathlessness on mild exertion, dizziness, or pale skin — these are classic signs that the body is short on oxygen. Your GP may also order it to monitor a known condition (such as iron deficiency, chronic kidney disease, or inflammatory bowel disease), to check in before or after a surgery, or as part of a routine health check. Because haemoglobin is part of the full blood count, it is usually interpreted alongside related measures — mean cell volume (MCV), which describes the size of your red cells; ferritin, which shows your iron stores; and iron studies, which map how iron moves through your body. Trends over time are more informative than a single result.
Reference range (Australia)
Sex-specific intervals apply: the range for men is higher than for women. Australian Red Cross Lifeblood (the national blood service) states: "For men, the haemoglobin reference range (that is, the range considered normal) is 125–185 grams per litre (g/L) and for women it's 115–165 g/L." Individual laboratories may use slightly different intervals depending on their assay platform — the range printed on your own report is the one that applies to you. Jia to confirm against Sonic's actual assay intervals before publish.
Reference intervals vary between laboratories. Always use the range printed on your own report.
What your result means
A haemoglobin below the reference range is called anaemia — a reduction in the blood's ability to carry oxygen. Anaemia is one of the most common blood-test findings, affecting about 7.7% of Australian adults. The most common cause is iron deficiency — depleted iron stores, usually from low dietary intake or blood loss. Other causes include a shortage of vitamin B12 or folate (both needed to make red blood cells), and chronic disease, where ongoing inflammation can slow red blood cell production. Recent blood loss, or a problem with the bone marrow or red cell survival, can also play a part. Low haemoglobin doesn't tell your GP why it's low — follow-up tests such as iron studies, ferritin, vitamin B12 and MCV (mean cell volume, the average size of your red cells) help find the cause. It is worth talking this result over with your GP, who will read it together with your symptoms and history to work out the right next step for you.
Your haemoglobin sits within the range on your report, suggesting your blood's oxygen-carrying capacity is adequate. Keep in mind that the lower end of normal and the upper end of abnormal are close together: if you have symptoms such as persistent tiredness or breathlessness, it's still worth a conversation with your GP, who can look at trends and the rest of your full blood count rather than relying on a single result.
A haemoglobin above the reference range means your blood contains more oxygen-carrying protein than usual. Most commonly this reflects dehydration, which concentrates the blood temporarily. Other causes include smoking (carbon monoxide triggers the body to make more haemoglobin), living at high altitude, or a condition called polycythaemia (excess red blood cell production) — either as a normal adaptation or, less often, as a bone marrow condition called polycythaemia vera. A temporarily raised result often resolves once hydration is restored. Worth mentioning to your GP at your next visit rather than reading too much into a single result: they can tell you which is most likely for you.
What can affect your result
Haemoglobin is influenced by several overlapping factors. Iron availability is the biggest one. Iron is the core of the haemoglobin molecule; without it, red cells are small and pale (a pattern called microcytic anaemia, because the cells are micro = small). Ferritin (your iron-storage protein) and iron studies are the tests that pin this down. Vitamin B12 and folate are needed for the DNA replication that produces red blood cells. When either is deficient, the cells that form are large and immature — a pattern called macrocytic anaemia (macro = large). MCV (mean cell volume) on your full blood count flags this. Hydration matters more than many people realise: when you are dehydrated, less water in the blood means red cells are more concentrated, so the haemoglobin reading looks higher. A well-hydrated repeat can look quite different. Altitude and smoking both trigger the body to make more haemoglobin naturally, as a response to lower oxygen availability. Chronic inflammation — from conditions such as rheumatoid arthritis, kidney disease, or cancer — can suppress red blood cell production directly, causing anaemia of chronic disease even when iron stores are adequate. Certain medicines can also affect haemoglobin: long-term non-steroidal anti-inflammatory drugs (NSAIDs) can cause gut bleeding that slowly lowers haemoglobin; some chemotherapy drugs directly suppress the bone marrow. Your GP will weigh up your medications when interpreting the result.
When to act
If your haemoglobin is below the reference range on your report, that is worth a conversation with your GP. They can look at the result together with your MCV, ferritin, and iron studies, alongside your symptoms and history, to work out whether this reflects iron deficiency, a vitamin deficiency, chronic disease, or another cause — and what, if anything, should happen next. If your result is above the range, your GP can tell you whether this is likely a temporary effect of dehydration or something that warrants a follow-up blood count. A trend over two or three results is usually more meaningful than a single reading. If you have symptoms (persistent tiredness, breathlessness, dizziness) even with a result at the lower end of normal, that is also worth raising. This page is general information and is not a substitute for advice from your GP.
Frequently asked questions
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