Ferritin test

What is it?

Ferritin is a protein that binds iron and stores it in the body. This test measures its level in the blood — in other words, how much iron is stored.

It is one of the iron tests, alongside serum iron, transferrin (the protein that moves iron around the body) and total iron-binding capacity (TIBC).

Why is it done?

It is often ordered with other iron tests to help diagnose iron deficiency anaemia, haemochromatosis (too much iron), some liver diseases or restless legs syndrome, to monitor long-term conditions that affect iron, and to check whether iron treatment is working.

Symptoms of low iron that may lead to the test include shortness of breath, weakness or tiredness, dizziness, an irregular heartbeat and pale skin. Symptoms of high iron include weakness or tiredness, joint pain (often in the knees or hands), abdominal pain and skin that looks grey or bronze.

It may also be done if other tests show a low haematocrit or haemoglobin, or to find low iron early in people at higher risk, such as pregnant women and those with heavy periods.

Preparation

Your doctor may ask you to fast for 12 hours beforehand, and the test is usually done in the morning because blood iron levels change during the day.

How is it done?

A health professional takes a blood sample from a vein in your arm with a small needle. It usually takes less than five minutes, and you may feel a brief sting.

Understanding the result

Low ferritin may mean iron deficiency anaemia or another low-iron condition. Untreated, it can lead to heart problems, infections, and slower growth and brain development in children.

High ferritin usually means too much iron in the body. Other causes include inflammation (after infection or surgery), autoimmune disorders, liver disease, cancer, obesity, alcohol use disorder and an overactive thyroid.

The source gives no numeric ranges: rely on the reference range in your laboratory report and on your doctor's interpretation.

Risks and side effects

There is very little risk: you may have slight pain or bruising where the needle went in, which usually fades quickly.

Limits of the test

An abnormal result doesn't always mean a condition that needs treatment, as some medicines raise or lower ferritin. Iron tests are read alongside symptoms, age, medical history and other blood tests.

After the test

The NHS says haemochromatosis is usually diagnosed with a full blood count, a liver test, a transferrin saturation test and ferritin, then a genetic test if the results suggest it — and that high iron has other causes, such as long-term liver disease, frequent blood transfusions, heavy drinking and iron supplements.

For iron deficiency anaemia, a full blood count is usually the first test, and MedlinePlus says most conditions with too little or too much iron can be treated with medicines, diet or other therapies.

• Complete blood count (CBC)Lab test
• AnemiaCondition

Common questions