What is haemoglobin (Hb) on a blood test?
Haemoglobin is the iron-containing protein inside your red blood cells that carries oxygen from your lungs to the rest of you.
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The short answer
Haemoglobin is the iron-containing protein inside your red blood cells that carries oxygen from your lungs to the rest of you. A low haemoglobin is what most people mean by anaemia. At Epicentre it's R64 on its own, or part of the R206 full blood count.
What does Haemoglobin measure?
Every red blood cell is essentially a bag of haemoglobin. Each molecule holds four iron atoms, and each iron atom binds one molecule of oxygen. That's the whole job: collect oxygen in the lungs, release it in the tissues.
When haemoglobin is low, less oxygen reaches your muscles and brain, which is why anaemia feels like exhaustion, breathlessness on stairs and difficulty concentrating rather than anything obviously to do with blood.
Haemoglobin tells you there's a problem. It doesn't tell you why, which is what the rest of the full blood count and the iron studies are for.
What does a high or low Haemoglobin mean?
Before reading anything into either, remember how reference ranges work. They're built so that 95% of healthy people fall inside them, which means roughly 1 in 20 perfectly normal results sits outside by definition. A single flagged value in an otherwise normal panel is common, and the pattern across related markers matters far more than any one number.
Not sure whether you need this on its own or as part of a panel? Tell us what you're trying to find out.
Ask us on WhatsAppSee all 102 markersWhat else affects Haemoglobin?
These are the things that move the number without anything being wrong, and they're worth knowing before you worry about a result.
- Hydration
- Dehydration concentrates your blood and raises haemoglobin. Over-hydration dilutes it.
- Heavy periods
- One of the most common and most under-recognised causes of low haemoglobin in women.
- Altitude and smoking
- Both raise it, because your body compensates for less available oxygen.
- Pregnancy
- Blood volume expands faster than red cell production, so a lower haemoglobin is expected.
The functional view
The functional view of haemoglobin is mostly about what sits behind it, because by the time haemoglobin falls, the problem usually started some time ago.
Ferritin is the marker that moves first. Iron stores can be substantially depleted while haemoglobin is still comfortably inside its range, which is why someone can be exhausted, be told their haemoglobin is normal, and be entirely right that something is wrong.
That is the case for reading haemoglobin with ferritin and MCV rather than on its own, and for paying attention to a haemoglobin that has drifted down within range rather than waiting for it to fall out of it.
Where this marker sits in the bigger picture
Cellular transport
How things move around the body. Haemoglobin is the oxygen carrier, so it is transport in its most literal form.
This is the thinking behind the functional health report that comes with every blood order at Epicentre. It places each marker on a scale that shows the optimal band as well as the standard range, ranks what needs attention, and compares each result to your last one. Two people with the same "normal" can get very different reports.
Worth being clear about the limits, though. Functional optimal ranges are educational reference recommendations rather than diagnostic thresholds, they are not universally agreed, and a value inside a standard laboratory range is not a disease. What the functional view offers is a direction and a conversation, not a verdict. Both readings of your result are useful, and the standard one is still the one your doctor works from.
Which markers is it read with?
The full blood count at R206, which reports haemoglobin alongside MCV, MCH and RDW. Those tell you what kind of anaemia it is. Then ferritin R206 for iron stores and vitamin B12 R206.
Haemoglobin test
R64Walk in at any branch, no appointment and no doctor's referral if you're paying cash. Results in 2 to 5 working days, and every blood order comes back with a functional health report that puts each marker on a plain-English scale at no extra cost.
See it on the test list Ask us on WhatsAppWhich packages include Haemoglobin?
Haemoglobin is on 26 panels, since it comes with every full blood count. These are the common ones.
Routine antenatal screening.
See what's included →R975Antenatal Panel (Including HIV)Includes haemoglobin.
See what's included →R1,090Bodybuilding Health Blood TestIncludes haemoglobin.
See what's included →R1,113Visa and Employment Medical PanelIncludes haemoglobin.
See what's included →R1,139Inflammation and Autoimmune PanelIncludes haemoglobin.
See what's included →R1,409Comprehensive Metabolic Panel (CMP)The broad organ-function panel.
See what's included →Plus 20 more panels that include haemoglobin. See all packages or tick your own on the pricelist.
Worth reading next
Where can I test Haemoglobin in South Africa?
All three are open Monday to Friday, 08:30 to 16:00, and closed on public holidays. Medical aid rates are roughly 20% higher than the cash rate and generally need a doctor's request with an ICD-10 code.
Basically
Haemoglobin is R64 at Epicentre and you don't need a referral for it. One result slightly outside the range is common and usually means very little on its own. What matters is the pattern with the markers it's read alongside, and whether it has changed since last time.
Frequently asked questions
What is a normal haemoglobin level?
Reference ranges differ by sex and by laboratory, and your result prints with the range that applies to you. Ranges are also different in pregnancy and childhood. A result slightly outside the range is common and not the same as a diagnosis.
What does low haemoglobin mean?
It means anaemia, which is a finding rather than a diagnosis. The common causes are iron deficiency, vitamin B12 or folate deficiency, blood loss including heavy periods, and chronic disease. Working out which one needs the rest of the full blood count, particularly MCV, plus ferritin and B12.
Can dehydration affect haemoglobin?
Yes. Dehydration concentrates your blood, so haemoglobin reads higher than it truly is, and over-hydration does the reverse. It's one reason a small change between two tests isn't necessarily a real change.
What's the difference between haemoglobin and ferritin?
Haemoglobin is the oxygen-carrying protein circulating in your red cells right now. Ferritin is your stored iron. Ferritin falls first, before haemoglobin drops, so you can have depleted iron stores and a normal haemoglobin. That's why ferritin catches iron deficiency earlier.
What is the functional range for haemoglobin (Hb), and how is it different?
A standard laboratory reference range is statistical: it is built so that about 95% of a reference population falls inside it, and it is designed to identify people who need treating. A functional or optimal range is narrower and asks whether a result is drifting in a direction that may matter over time, even while it stays inside the standard range. Functional optimal ranges are educational reference recommendations rather than diagnostic thresholds and are not universally agreed. A result inside a standard laboratory range is not a disease. Epicentre includes a functional health report with every blood order, showing each marker against both ranges alongside the standard laboratory result your doctor works from.
Other markers explained
This page is general health information and not a medical diagnosis. Epicentre Aids Risk Management (Pty) Ltd, practice number 1117394, provides diagnostic laboratory testing: we don't diagnose, prescribe or treat, and results are intended to inform a consultation with your doctor. Medically reviewed by Dr Samantha Naidoo, MB ChB, FCP (SA), Medical Director. Prices are 2026 cash rates including 15% VAT and can change without notice. Reference ranges vary between laboratories and your result prints with the range that applies to you.