What does Ferritin measure?

The test measures ferritin circulating in blood. Low ferritin can support iron deficiency in the right context, while a high result is less specific and may reflect iron excess or an inflammatory response. ^{1, 2}

What the result can—and cannot—tell you

It can help show

How much ferritin is present in the sample ¹
Whether iron stores may be low ^{1, 2}
A trend when interpreted with other iron studies ^{1, 2}

It cannot show by itself

The cause of an abnormal value by itself ^{1, 2}
Whether all body tissues have adequate iron ²
Whether iron supplements are appropriate for you ¹

Reference range vs. clinical decision

Use the range on your own laboratory report.

Ferritin reference intervals vary by laboratory, age, sex and clinical context. Inflammation can raise ferritin even when available iron is limited. Interpret the laboratory's range alongside a blood count, transferrin saturation and relevant symptoms or conditions. ^{1, 2}

Context that can change interpretation

Recent illness or chronic inflammation ^{1, 2}
Liver disease and alcohol use ^{1, 2}
Menstruation, pregnancy, blood donation, bleeding and iron supplementation ¹

Preparing for the test

Preparation depends on the other iron tests ordered. Some laboratories request fasting or a morning sample. Follow the performing laboratory's instructions. ¹

Common questions

Does high ferritin always mean too much iron?

No. Ferritin is an acute-phase reactant and can increase with inflammation, infection or liver disease. Other tests and history are needed. ^{1, 2}

Should I take iron if ferritin is low?

Do not start treatment from this page alone. A clinician can confirm the pattern, look for a cause and recommend an appropriate dose if needed. ¹

Sources and evidence notes

Ferritin Blood TestMedlinePlus · 2024
Patient-oriented overview and interpretation limits.
WHO guideline on use of ferritin concentrations to assess iron statusWorld Health Organization · 2020
Guidance on ferritin interpretation, including inflammation.

Revision history

2026-08-17
Initial evidence-led guide and source map published. — Syed Jafri

Ferritin (Ferritin)