Ferritin blood test: what it measures and what your result means

Medically reviewed by Dr Lebeth Jacob · 21 October 2026

Quick answer: Ferritin is a protein that stores iron in your body. A ferritin blood test shows how much iron you have in reserve. A low result usually means your iron stores are running down, often before anaemia develops. A high result can mean too much iron, but is more often caused by inflammation, infection, liver problems or alcohol.

What is ferritin?

Your body keeps most of its spare iron locked inside ferritin, mainly in the liver, spleen and bone marrow. A small amount of ferritin passes into your blood, and that amount tracks how much iron you have stored.

Ferritin is not the same as iron. A serum iron test measures iron moving in your blood right now, which changes through the day. Ferritin shows your reserves, so it is usually the first test used to check for iron deficiency.

Why is ferritin tested?

  • You feel tired, breathless or weak, or look pale
  • You have heavy periods, are pregnant or have recently given birth
  • You eat little or no meat, or follow a vegan diet
  • You have hair shedding, restless legs or brittle nails
  • You give blood often or train hard for endurance sport
  • You are checking iron levels on supplements or after treatment

What does a low ferritin result mean?

Low ferritin almost always means low iron stores. Common reasons are:

  • Blood loss, most often from heavy periods
  • Pregnancy, when the body's iron needs rise
  • Not enough iron in the diet
  • Poor absorption, for example with coeliac disease
  • Bleeding from the stomach or bowel, which may not be visible

Ferritin can fall well before haemoglobin does. So you can have low iron stores with a normal full blood count.

What does a high ferritin result mean?

Ferritin rises whenever the body is inflamed, so a high result does not always mean too much iron. Common reasons are:

  • A recent infection or illness
  • Inflammatory conditions such as arthritis
  • Liver conditions, including fatty liver
  • Regular or heavy alcohol use
  • Being overweight, or having type 2 diabetes
  • Iron overload, such as the inherited condition haemochromatosis

A doctor will often look at transferrin saturation and liver tests alongside ferritin to tell these apart.

What can affect your result?

  • A cold, infection or injury in the past few weeks can raise ferritin
  • Iron tablets or iron-rich supplements raise it over time
  • Alcohol in the days before the test can raise it
  • You don't usually need to fast for ferritin alone, but some tests that include it ask you to. Follow the instructions for the test you book.

When to see a GP

Your results report shows the laboratory's normal range and flags any result outside it. Speak to your GP if:

  • Your ferritin is flagged low or high
  • You have symptoms of anaemia, such as tiredness, breathlessness or palpitations
  • You are a man, or a woman past the menopause, with low ferritin and no clear reason
  • You notice black or bloody stools, or lose weight without trying

Call 999 or go to A&E for chest pain, severe breathlessness, fainting, or vomiting blood.

How we test ferritin

You can have ferritin tested with a blood sample taken at one of our 250+ partner clinics, or with a finger-prick kit at home. Samples are analysed by a UKAS-accredited laboratory. Results are usually ready in 3–5 working days, with a doctor's comments on every result.

Tests that include ferritin

Prices for in-clinic tests include your appointment. Compare every test with ferritin in the biomarker explorer

Frequently asked questions

What is a dangerously low ferritin level?

There is no single number that is dangerous for everyone. What matters is how far below the laboratory's range your result is, your haemoglobin, and your symptoms. A very low result with symptoms of anaemia should be checked by a GP promptly.

Is ferritin the same as iron?

No. Ferritin is the protein that stores iron. A serum iron test measures iron in the blood at that moment. Ferritin is the better guide to your iron reserves.

Can you have low ferritin with normal haemoglobin?

Yes. Iron stores run down first, and haemoglobin falls later. Low ferritin with normal haemoglobin is called iron deficiency without anaemia, and it can still cause tiredness.

Is low ferritin a sign of cancer?

Usually not. The most common causes are periods, pregnancy and diet. But unexplained low iron in men and in women past the menopause is always looked into, because it can come from hidden bleeding in the bowel. See your GP if this applies to you.

How can I increase my ferritin levels?

First find out why it is low. Iron-rich foods such as red meat, beans, lentils and dark green vegetables help, and vitamin C with meals improves absorption. Tea and coffee with meals reduce it. Take iron supplements only on medical advice, because too much iron is harmful.

How long does it take for ferritin to go up?

With treatment, ferritin usually rises over a few months, not weeks. A repeat test after about three months shows whether it is working.