Iron deficiency without anaemia: what a low ferritin means

Your blood result is normal, the GP tells you. Yet you drag yourself through the day, fall asleep on the sofa and your hair seems to be thinning. That is not making a fuss: your haemoglobin can sit neatly within range while your iron store is nearly empty. Ferritin, the marker that measures that store, has then already dropped, but you are not yet anaemic.

To my mind this is one of the most missed causes of fatigue in women. If only haemoglobin is measured, a low ferritin can stay completely under the radar, while you have not felt yourself for months. Below you read why your body does this, which complaints fit it and when a ferritin measurement really adds something.

The difference between iron deficiency and anaemia

Iron deficiency and anaemia are not the same, and that distinction decides everything about this result. An iron deficiency starts with a falling store. Only when that store is truly empty does your haemoglobin drop and do you speak of iron-deficiency anaemia. Between those two moments there is often a long, silent phase.

Your body protects your haemoglobin for as long as possible. It first draws iron from the store before the production of red blood cells suffers. So you can have a low ferritin with a normal haemoglobin for months, and still feel complaints in that period. The NHG (Dutch College of General Practitioners) Anaemia guideline describes these stages too: a shortage of iron store precedes the actual anaemia.

A standard blood test that only looks at haemoglobin sees only the last row. The two rows above it can already wear you down without the result showing anything.

Which complaints fit a low ferritin?

A low ferritin often gives vague complaints that you do not immediately link to iron. Tiredness comes first, but there are more signals that together form a pattern.

• Persistent fatigue, even after enough sleep
• Quickly out of breath or a pounding heart on exertion
• Hair loss or brittle nails
• Concentration problems or a foggy feeling in your head
• Restless legs, especially in the evening

These complaints also fit other causes, like an underactive thyroid or a vitamin shortage. So a single symptom says little. Also read our overview on which blood values to test for fatigue, and if your haemoglobin is lowered too, the piece on anaemia symptoms in women.

Why a normal haemoglobin does not reassure you

If only your haemoglobin is measured, a low ferritin can go unnoticed. You then hear that your blood is fine, while your store is nearly empty. That explains why some women keep feeling tired despite a normal result.

So with unexplained tiredness it is useful to include the ferritin. Thuisarts.nl, the public site of the Dutch College of General Practitioners, also names ferritin as the value that reflects your iron store. A lowered ferritin with a normal haemoglobin can be a lead that is otherwise missed. Always discuss a low result with your GP.

What exactly do you test?

For a complete picture you look at your store and at the iron in your blood. Together they show whether you have a deficiency and how far it has progressed.

• Ferritin is the iron store and falls first.
• Iron (serum) shows how much iron is in your blood at that moment.
• Transferrin is the transport protein and often rises when your store is low.
• Haemoglobin shows whether anaemia is already present.

The Iron Status measures these values in one draw, so you know not only whether you have a deficiency, but also which phase. Want to know how to keep your iron up? Read our article on preventing iron deficiency with nutrition and supplements.

When is testing worthwhile?

A ferritin measurement is mainly useful with unexplained tiredness, especially if you lose or need extra iron. Women are at higher risk through menstruation, pregnancy and breastfeeding. The Netherlands Nutrition Centre (Voedingscentrum) also points out that menstruating women and pregnant women have a higher iron need than the average adult, which puts the store under pressure sooner.

Consider a ferritin measurement if you recognise this:

• You are persistently tired while an earlier result was normal
• You have heavy or long periods
• You have been pregnant or are breastfeeding
• You eat little or no meat

At Lunara you test without a referral and your result gets context per value from a BIG-registered doctor. You do not simply supplement a low ferritin yourself: too much iron is not desirable either, so always discuss supplementation with your GP.

Frequently asked questions

Can ferritin be too low with a normal Hb?

Yes. Your store (ferritin) falls before your haemoglobin suffers. So you can have a low ferritin with a normal haemoglobin, and still feel complaints.

Which ferritin value is too low?

That depends on the laboratory and your situation. A value at the bottom of or just below the reference range can already cause complaints, especially in women. So read your result together with a doctor.

Should I take iron tablets straight away?

Not without consultation. Too much iron can be harmful, and the cause of the deficiency also deserves attention. Discuss supplementation and the right dose with your GP.

References

1. NHG Anaemia guideline. Dutch College of General Practitioners. Available via nhg.org.
2. Thuisarts.nl. Iron-deficiency anaemia. Dutch College of General Practitioners. Available via thuisarts.nl.
3. Netherlands Nutrition Centre (Voedingscentrum). Iron: function, need and sources. Available via voedingscentrum.nl.

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