Anaemia and iron deficiency: symptoms, ferritin and which blood test gives insight

Anaemia and iron deficiency are often confused, but they are not the same. Iron deficiency is the most common nutritional deficiency worldwide, and it can cause symptoms before anaemia develops (Pasricha 2021). We often see people only think about iron once they have been exhausted for months. That is a shame, because your iron stores usually drop much earlier, and a simple blood test can show it.

This overview explains the difference between iron deficiency and anaemia, which symptoms may fit, and which values such as ferritin, haemoglobin and transferrin give insight. Think of it as the hub: the separate topics are worked out in their own articles below.

What is the difference between iron deficiency and anaemia?

In short: iron deficiency means your iron stores are too low, and anaemia means you have too few or too poor red blood cells. The two are linked, but not identical. You need iron to make haemoglobin, the pigment that carries oxygen. When your stores run out, your body eventually makes less haemoglobin. Only when haemoglobin drops below a threshold do doctors call it anaemia.

So you can have iron deficiency while your haemoglobin is still normal. Your stores are low, but your body just keeps production going. That is iron deficiency without anaemia, and it is often the first phase. Read more in iron deficiency without anaemia. Anaemia can also have causes other than iron, such as low vitamin B12 or folate. A broader look is in anaemia symptoms and causes.

What does iron do in your body?

Iron is a building block for oxygen transport and energy. Most of it sits in your haemoglobin, and a part is stored as a reserve, mainly as ferritin. Picture it as a cupboard with a working supply and a reserve supply. You draw on the reserve first when you take in too little or lose too much. Only when that cupboard is empty does your haemoglobin drop.

According to the Dutch NHG Anaemia guideline, iron deficiency is the most common cause of anaemia in Dutch primary care. Your body has no active way to get rid of excess iron, so the balance runs mainly through absorption and loss.

Which symptoms may point to low iron?

The symptoms are often vague and gradual. They build slowly, so you easily attribute them to a busy period. That is exactly why a blood test helps: it takes the guesswork out.

• Persistent tiredness that does not lift with rest
• Paleness, especially in the face or inner eyelids
• Getting short of breath or palpitations on exertion
• Cold hands and feet
• Hair loss or brittle nails
• Trouble concentrating or light-headedness
• Restless legs, especially in the evening

One symptom on its own says little. It is about the pattern, and whether symptoms persist. Your GP can help decide whether iron plays a role.

Who is more likely to have low iron?

Anyone can develop low iron, but some groups meet it more often, usually through blood loss or a higher need for iron.

• Menstruation, especially with heavy or long bleeding
• Pregnancy and the recovery period after it
• A diet low in iron-rich foods
• Intensive endurance sport
• Stomach or gut conditions affecting absorption or blood loss

I go deeper for women in iron deficiency in women, and for athletes in iron and endurance.

Which blood values give insight into your iron status?

For what a number means, separate articles go deeper: read about your ferritin, haemoglobin, MCV or transferrin, and about the ferritin level explained and ferritin and iron storage.

What do your iron values mean together?

Single values say less than the combination. A low ferritin with a high transferrin and a low saturation fits iron deficiency (Camaschella 2015). If haemoglobin also drops, it is iron-deficiency anaemia. There is a catch: ferritin rises temporarily with inflammation or hard exercise, even when your stores are actually low. How the transport values work is covered in transferrin and saturation. A broader iron test with ferritin and more often gives more grip than one value.

Iron deficiency without anaemia

One of the most common questions we hear: can I have iron deficiency while my haemoglobin is normal? Yes. In the early phase your stores are low while your body keeps haemoglobin going. You can already have symptoms. Read on in iron deficiency without anaemia.

Too much iron: is that possible?

Yes. Iron can be too high, for example in the inherited condition haemochromatosis, where the body absorbs and stores too much iron (Powell 2016). Read more in too much iron and haemochromatosis.

Iron and diet

You get iron from food, and not all of it is absorbed equally. According to the Dutch Voedingscentrum, iron is found in meat, legumes, whole grains and green vegetables, and vitamin C helps absorption of plant iron. How absorption works is covered in raising iron through diet.

When to have your iron tested?

There is no single rule. Some people test when symptoms persist, or when they lose a lot of blood or train hard. To measure your iron status without a referral, you can have your iron status tested or an anaemia panel at Vitalcheck. Every result is reviewed by a BIG-registered doctor.

What can you do about abnormal values?

An abnormal value is not a diagnosis, but a signal. The next step is almost always a conversation with your GP. Iron values can fluctuate, and a low ferritin sometimes calls for finding the cause of the loss. Where fatigue plays a big role, the always tired overview is a logical next step.

References

• Pasricha SR, et al. Iron deficiency. Lancet. 2021. PMID: 33285139.
• Camaschella C. Iron-deficiency anemia. N Engl J Med. 2015. PMID: 25946282.
• Powell LW, et al. Haemochromatosis. Lancet. 2016. PMID: 26975792.
• NHG-Standaard Anemie. Dutch College of General Practitioners.
• Voedingscentrum. Iron.

Every blood test result includes a professional assessment from a BIG-registered doctor. For treatment decisions, discuss your results with your GP.