You are tired, but not just tired: one flight of stairs and you are out of breath, and a colleague asks if you are ill because you look so pale. That pattern of fatigue, paleness and breathlessness is a classic signal of anaemia. The trap is to leave it there, because anaemia is a finding, not a final diagnosis. The real question is always: what is causing it?
What I tell people: a low haemoglobin tells you that something is wrong, not what. Only once you know the cause do you know what to do about it.
What are the symptoms of anaemia?
The complaints arise because your tissues receive less oxygen. They are broad and can have other causes, so they do not automatically point to anaemia.
- Persistent fatigue: often the first signal
- Pale skin: sometimes also pale inner eyelids
- Shortness of breath: especially on exertion
- Palpitations or dizziness
Unsure where your fatigue comes from? Read why am I so tired and which blood values explain it.
Which blood values reveal anaemia?
Anaemia is established with a blood test. Several values together show whether it is present and help find the cause.
| Blood value | What it adds | Direction |
|---|---|---|
| Haemoglobin | The core value that proves anaemia | Low = anaemia |
| MCV | The size of your red blood cells | Low points to iron, high to B12/folate |
| Ferritin | Your iron store | Low = iron deficiency as cause |
| Vitamin B12 | Needed for red blood cells | Low in macrocytic anaemia |
| Folate | Needed for cell division | Low in macrocytic anaemia |
The MCV is the key that points the direction: small cells (low MCV) fit iron deficiency, large cells (high MCV) fit a deficiency of vitamin B12 or folate. Read our explainer on the complete blood count and on the ferritin level.
What are the most common causes?
Iron deficiency tops the list, for example through blood loss during menstruation or a one-sided diet. According to the World Health Organization (WHO), iron deficiency is the most common cause of anaemia worldwide. A deficiency of vitamin B12 or folate can also cause anaemia. Sometimes the cause lies elsewhere, such as a chronic condition, which is why an assessment always belongs with it.
An anaemia panel measures the relevant values together, or you can look specifically at your iron status.
The three types of anaemia by your MCV
Doctors often classify anaemia based on the size of your red blood cells, the MCV. That is not a detail for specialists, because it determines the likely direction of your cause.
- Microcytic (small cells, low MCV): usually points to iron deficiency. The most common form, especially in women through menstrual blood loss.
- Macrocytic (large cells, high MCV): points to a deficiency of vitamin B12 or folate, or sometimes to heavy alcohol use.
- Normocytic (normal cell size): occurs with chronic conditions or acute blood loss, and often calls for further investigation.
This classification is exactly why a standalone haemoglobin measurement falls short. Without the MCV and the iron, B12 and folate values, you know there is anaemia, but not which way to look.
What happens after the result?
The approach follows the cause, not the other way around. For iron deficiency it is about replenishing and finding the source of the loss, for example heavy menstruation. For a B12 or folate deficiency, treatment targets that specific vitamin. If a chronic condition lies underneath, that is the real focus. The NHG (Dutch College of General Practitioners) stresses that iron supplementation only makes sense once iron deficiency is actually proven, because blindly taking iron with another cause does not help and can even mask what is really going on.
When should you test?
Consider testing with persistent fatigue plus paleness or breathlessness, with heavy menstruation, around pregnancy, or if you belong to a risk group (vegetarian diet, older adults, gut complaints). The NHG (Dutch College of General Practitioners) guideline on anaemia advises doctors to always uncover the cause before treating established anaemia.
Frequently asked questions
Is anaemia always due to iron deficiency?
No. Iron deficiency is the most common cause, but vitamin B12, folate and other conditions can also play a role. The cause determines the approach.
Can I fix anaemia with food?
With a mild iron deficiency, food can help, but that depends on the cause. Discuss confirmed anaemia with your GP before supplementing on your own.
Is anaemia dangerous?
Mild anaemia mainly causes complaints such as fatigue and breathlessness and is usually well treatable once the cause is known. Left untreated or in a severe form, it can significantly limit your daily functioning and put extra strain on your heart. That is why it is wise not to ignore persistent complaints and to have the cause investigated rather than wait it out.
My advice: see anaemia as a clue and look for the cause together with your GP. Want to test specifically? Build a custom blood test. Every result at Vitalcheck is reviewed by a registered doctor. A blood value is not a diagnosis: discuss symptoms and treatment with your GP.
Sources
- NHG guideline Anaemia. Dutch College of General Practitioners. Accessed 2026.
- World Health Organization. Anaemia: key facts. 2023.
- Thuisarts.nl / NHG. I have anaemia. Accessed 2026.
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