Haemoglobin (Hb) – The blood count

What is Haemoglobin (Hb)?

Haemoglobin is the protein in red blood cells that binds oxygen in the lungs and releases it into the body's tissues. The test is taken in a standard blood draw and is part of the complete blood count (CBC).

Why is Haemoglobin (Hb) measured in a health check?

Haemoglobin is a basic test in almost all health checks because it both catches anaemia and gives an initial signal of bleeding, iron deficiency, vitamin deficiency, or bone marrow disease.

High and low values

High value: High values can be due to dehydration, smoking, sleep apnoea, or staying at high altitudes, and in rare cases, a bone marrow disease.

Low value: Low values mean anaemia. The most common causes are iron deficiency, B12 or folate deficiency, chronic inflammation, and bleeding.

Reference ranges differ between laboratories, sexes and ages and are stated in your result. The information here does not replace medical assessment.

How is haemoglobin measured in a health check?

Haemoglobin is analysed as part of a full blood count in a standard venous blood draw. The test requires no fasting and can be taken at any time of day. A health-check blood test almost always includes haemoglobin, since it's inexpensive to analyse while providing a lot of information about both oxygen transport and bone marrow function.

Severe dehydration can temporarily raise haemoglobin because the blood becomes more concentrated, while a lot of fluid shortly before the test can lower it slightly. Drink normally before the test and avoid intense exercise in the hours beforehand, so the value is as representative as possible.

What does a full blood count show beyond haemoglobin?

Haemoglobin is always interpreted together with the other parts of a full blood count. Together they show why a value deviates, not just that it does.

• MCV — the size of the red blood cells, pointing towards iron deficiency (small) or B12 and folate deficiency (large)
• Haematocrit (EVF) — the proportion of red blood cells in blood volume, affected by fluid balance
• Leukocytes — white blood cells, which rise with infection and inflammation
• Platelets — important for blood clotting
• Ferritin and iron — show the stores behind a falling haemoglobin

Which symptoms make haemoglobin especially relevant?

Anaemia often develops so slowly that the body has time to adapt. Typical signs are fatigue that doesn't improve with rest, breathlessness on stairs, palpitations, headache, paleness and reduced concentration. Many describe that exercise feels harder than usual without having changed anything.

Haemoglobin is also relevant with dark stools, heavy periods or recent surgery, since blood loss is a common cause of falling haemoglobin. If a health-check blood test shows low haemoglobin, it's important that the cause is investigated by a doctor rather than simply treated with supplements.

How often should haemoglobin be checked?

For healthy adults without symptoms, a check every other year as part of a health check is usually enough. Once anaemia has been diagnosed, the value is followed more closely, often after six to twelve weeks of treatment. Blood donors, pregnant women and people with chronic disease are checked according to their care provider's routines, which can be considerably more frequent than that. Someone who regularly books a health check also builds a combined history to lean on if a single value ever needs explaining.

What causes low haemoglobin in different groups?

The cause behind low haemoglobin differs a great deal depending on who is affected, and a health check becomes most useful when the result is interpreted in light of that background. In people who menstruate, heavy or prolonged bleeding is the most common explanation, particularly with a non-hormonal coil or with conditions such as endometriosis. The iron loss month after month can be greater than diet can replace, even for someone who eats a varied diet.

In older adults the picture is often more complex. Chronic inflammation, reduced kidney function, medicines that affect the stomach lining and a less varied diet all contribute together, and sometimes several causes are present at once. In athletes, particularly in endurance sports, haemoglobin can look lower without this being true anaemia, since hard training increases blood volume and dilutes the haemoglobin. At the same time, genuine iron deficiency does occur in athletes because of sweat losses, some breakdown of red blood cells from repeated impact, and high energy demands. Vegetarians and vegans don't automatically have lower haemoglobin, but iron from plants is absorbed less efficiently by the body than iron from meat, which means the margins can narrow over time if the diet isn't well planned.

A health check cannot on its own establish why an individual's haemoglobin is low, but it gives a clear signal that a cause exists and needs to be clarified. Combining it with ferritin, MCV and sometimes B12 and folate makes it possible to see whether it's a matter of iron deficiency, another deficiency condition or a benign dilution effect from training, which determines whether the next step is diet, supplements or further investigation by a doctor.

• Menstruating people — heavy bleeding, non-hormonal coil, endometriosis
• Older adults — chronic inflammation, medicines, a limited diet, several causes at once
• Athletes — dilution of the blood from endurance training, but also genuine iron deficiency from sweat and physical load
• Vegetarians and vegans — reduced absorption of plant-based iron, most significant when margins are already small

How is haemoglobin interpreted over time and at follow-up?

A single haemoglobin value is a snapshot, while the real information often lies in the change. A value that stays stable year after year, even if it sits in the lower part of what's considered normal for that particular person, carries different weight than a value that has clearly fallen since the last health check. This is why it's valuable to save previous test results and compare them, rather than looking only at the most recent result on its own.

At follow-up after iron deficiency or anaemia has been detected, haemoglobin is usually checked again after a few weeks of treatment, to see that it's moving in the right direction. A rising haemoglobin confirms that the cause was reasonably well identified and that the treatment is working, while a lack of response is a sign that the cause needs further investigation. In a health check done regularly, for example every other year, each new result becomes a reference point that makes the next interpretation more reliable, especially for someone who knows they tend towards low iron.

The reference ranges given in the test result differ by sex, age and sometimes even between laboratories, which is one reason the same figure can be interpreted differently for different people. This means comparisons are best made against your own previous values rather than against someone else's result, and that an assessment of the trend across several health checks often says more than a single measured value.

• Sex and age — determine where your own range in the test result lies
• Chronic disease or inflammation — can produce a stable but lower value over time
• Medicines — some can affect blood formation and therefore haemoglobin
• Training level — high training volume can lower the value without this being anaemia

When should you seek care rather than book a health check?

A health check is a good tool for catching slow, low-symptom changes, but it isn't the right route for acute or severe symptoms. Severe breathlessness at rest, chest pain, rapid palpitations, blood in the stool or vomit, unusually heavy bleeding, or sudden and pronounced paleness should be assessed by a doctor straight away, not left waiting for a booked test appointment.

The same applies if fatigue and other symptoms appear quickly and clearly rather than gradually, since this can point to a more acute cause, such as bleeding, that needs to be found and stopped. Someone who already knows their haemoglobin is low and is waiting for investigation should also contact a doctor if new or worsening symptoms appear, rather than waiting for the next health check.

If the symptoms are instead mild and have been present for a long time, for example gradually increasing fatigue with no other warning signs, a booked health check is a reasonable first step to see whether haemoglobin and iron status provide an explanation. If the result turns out to be clearly abnormal, it's then quick to move on to a doctor with concrete evidence in hand, which often makes the further investigation more efficient.

• Breathlessness at rest or with light exertion
• Chest pain or rapid, irregular palpitations
• Blood in stool or vomit, or very dark, tarry stools
• Unusually heavy bleeding or sudden, pronounced paleness

Frequently asked questions about Haemoglobin (Hb)

Health checks that include Haemoglobin (Hb)

Haemoglobin (Hb) is included in 18 of Labkollen's health checks. Analysis name in the result: B-Hemoglobin.

• Man +

  49 markers

  Labkollens mest omfattande kontroll för män – inklusive testosteron, PSA och hjärt-kärlmarkörer.

  2 195 krMed prenumeration (årlig hälsokontroll): 1 756 kr

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• Kvinna +

  44 markers

  Labkollens mest omfattande kontroll för kvinnor – inklusive järnstatus, sköldkörtel och hormoner.

  2 195 krMed prenumeration (årlig hälsokontroll): 1 756 kr

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• Standard

  37 markers

  Bred hälsokontroll över blodsocker, blodfetter, blodvärde, lever, njurar, sköldkörtel och vitaminer.

  1 895 krMed prenumeration (årlig hälsokontroll): 1 516 kr

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• Seniorkollen

  32 markers

  Anpassad kontroll för dig över 65 med fokus på hjärta, njurar, sköldkörtel och näringsstatus.

  1 399 krMed prenumeration (årlig hälsokontroll): 1 119 kr

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• Gravid

  26 markers

  Kontroll under graviditet – blodvärde, järn, sköldkörtel, vitaminer och hCG.

  1 199 krMed prenumeration (årlig hälsokontroll): 959 kr

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• Hjärtkollen

  22 markers

  Blodfetter, ApoB och blodsocker för att bedöma risk för hjärt-kärlsjukdom.

  499 krMed prenumeration (årlig hälsokontroll): 399 kr

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• Vitamin- och mineralkollen

  18 markers

  D-vitamin, B12, folat, järn och mineraler för dig som vill kolla näringsstatus.

  1 199 krMed prenumeration (årlig hälsokontroll): 959 kr

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• Uthållighetssport

  16 markers

  För löpare, cyklister och simmare – järnstatus, energiomsättning och återhämtning.

  1 599 krMed prenumeration (årlig hälsokontroll): 1 279 kr

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• Lagsport

  16 markers

  För lagidrottare – energi, järn, återhämtning och stresshormon.

  1 599 krMed prenumeration (årlig hälsokontroll): 1 279 kr

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• Styrkesport

  15 markers

  För styrketräning – hormoner, muskelmarkörer, lever och mineraler.

  1 599 krMed prenumeration (årlig hälsokontroll): 1 279 kr

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• Kampsport

  15 markers

  För kampsportare – återhämtning, hormoner, inflammation och järn.

  1 599 krMed prenumeration (årlig hälsokontroll): 1 279 kr

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• Gymnastik och konståkning

  14 markers

  För teknikidrotter – benhälsa, järnstatus, sköldkörtel och tillväxtmarkörer.

  1 599 krMed prenumeration (årlig hälsokontroll): 1 279 kr

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• Hårkollen

  13 markers

  Markörer kopplade till håravfall: järn, zink, D-vitamin, B12 och hormoner.

  1 099 krMed prenumeration (årlig hälsokontroll): 879 kr

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• Mag- och tarmkollen

  13 markers

  Kalprotektin, glutenantikroppar och näringsstatus vid magbesvär.

  1 199 krMed prenumeration (årlig hälsokontroll): 959 kr

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• Riskbruk/alkohol

  10 markers

  Levervärden och CDT för att följa hur alkoholvanor påverkar kroppen.

  899 krMed prenumeration (årlig hälsokontroll): 719 kr

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• Järnkollen

  10 markers

  Full järnstatus vid trötthet, blekhet eller rikliga menstruationer.

  549 krMed prenumeration (årlig hälsokontroll): 439 kr

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• Reumatismkollen

  10 markers

  RF, anti-CCP och CRP vid ledvärk och stelhet.

  1 199 krMed prenumeration (årlig hälsokontroll): 959 kr

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• Glutenkollen

  9 markers

  Transglutaminasantikroppar och blodstatus vid misstanke om glutenintolerans.

  749 krMed prenumeration (årlig hälsokontroll): 599 kr

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Unsure which test you need? Start the test guide

Guides covering Haemoglobin (Hb)

• Trött hela tiden? Det här visar ett blodprov
• Hälsokontroll för kvinnor – vilka prover?
• Hälsokontroll efter 50 – vad bör ingå?
• Hälsokontroll efter 60 – vad bör ingå?
• Hälsokontroll för dig som tränar mycket