Low ferritin: symptoms, causes and what to do

A low ferritin means your iron store is running out. It often happens before haemoglobin drops, so your blood count can look perfect. In women before menopause the most common causes are heavy periods, pregnancy and too little iron in the diet. In men and after menopause, doctors look for blood loss first.

What low ferritin means

Iron carries oxygen all around your body. If you lose it or take in less than you need, your body uses the store and ferritin drops.

Watch out for numbers below 30: many lab reports for women call them normal, but the store is already low.

What causes low ferritin

• Heavy periods: The most common cause in women before menopause.
• Pregnancy and giving birth: Pregnancy needs a lot more iron, and you lose more at birth.
• Little iron on your plate: People who eat little meat often have a lower store.
• Iron is not absorbed: For example with coeliac disease, gastritis or some stomach medicines taken for years.
• Blood loss: Frequent blood donation, or small hidden losses from the gut. In men and after menopause, they are the first thing doctors look for.
• A lot of endurance sport: People who do a lot of endurance sport more often have low iron.

Symptoms

Some come while haemoglobin is still normal:

• Tiredness that does not go away
• Less strength in sport
• Restless legs in the evening
• More hair falling out than usual
• A craving to chew ice

If anaemia follows, you may also get short of breath, look pale and feel your heart racing. These symptoms can have other causes too: ferritin helps tell whether iron is involved.

Perfect blood count but low ferritin

This happens a lot. The store empties, but while some iron is left your body keeps making normal red blood cells. So the blood count looks fine. It is called iron deficiency without anaemia, and it can already make you tired. It is the best moment to act.

Which tests to read alongside it

These tests help show how serious the shortage is.

What your result means

The lower end of the scale, in ng/mL.

• Below 15: Iron deficiency. Your iron store is almost empty. Talk to a doctor to find the cause.
• 15 to under 30: Low store. Many lab reports for women call this normal, but the store is already low. Check your haemoglobin too, and look for the cause with your doctor.
• 30 up to your report’s limit, Usually 150 for women, 400 for men: Normal. Usually the store is enough, but inflammation can hide a low one. In the Rosa report you also see whether you are in your optimal range.

How to raise your ferritin

First find out why it is low: if the cause stays, ferritin drops again.

• What to eat: iron from red meat, fish and shellfish is absorbed best.
• Legumes, tofu and leafy greens have iron: eat them with citrus, kiwi or peppers, which help you absorb the iron in that meal.
• Keep tea and coffee away from meals: they slow absorption.
• With normal haemoglobin you start with food, and a supplement can help, especially if you have symptoms.
• If your haemoglobin is low too, you need a supplement, with the dose and length set by your doctor. Filling the store usually takes a few months.
• Iron tablets often make stools dark. If they are black like tar, or you feel weak or dizzy, call 112 or go to the emergency department.

When to worry

Talk to a doctor if:

• Your ferritin is below 15.
• Your haemoglobin is low too.
• You are a man, or a woman after menopause.
• You do not know why it is low.
• You lose weight for no reason: do not put off the visit.
• You see black stools or blood in your stools: call 112 or go to the emergency department.

With Rosa, a ferritin below 15 or a haemoglobin below 11 g/dL is always flagged to a doctor.

Frequently asked questions

Can low ferritin be a sign of cancer? Usually not. In women before menopause the most common causes are periods, pregnancy and diet. In men and after menopause, though, doctors look first for blood loss in the gut, which can sometimes come from a tumour. That is why, in men and after menopause, a low ferritin should always be seen by a doctor.

Low ferritin in pregnancy: what to do? You need a lot more iron in pregnancy, so it happens often. Talk to your obstetrician, who decides whether and how to supplement.

Low ferritin but normal iron: is that possible? Yes, it happens often. The iron in your blood changes a lot from day to day, ferritin much less. A normal iron does not mean the store is full.

Does low ferritin cause hair loss? It can, especially in women, although studies do not all agree. If you are losing more hair than usual, checking ferritin is a good start.

How long does ferritin take to come back up? With a supplement, the store usually fills up over a few months. If your haemoglobin was low too, it gets better within a few weeks.

Sources

• British Society of Gastroenterology, guidelines for iron deficiency anaemia in adults. Gut, 2021. PMID 34497146
• EASL clinical practice guidelines on haemochromatosis. Journal of Hepatology, 2022. PMID 35662478
• World Health Organization, guideline on the use of ferritin to assess iron status. Geneva, 2020. ISBN 978-92-4-000012-4