A ferritin test measures the amount of ferritin in the blood. Ferritin is a blood protein that contains iron. This test can be used to find out how much iron the body stores.

If a ferritin test shows that the blood ferritin level is low, it means the body's iron stores are low. This is a condition called iron deficiency. Iron deficiency can cause anemia.

If a ferritin test shows high ferritin levels, it most often means swelling in the body, called inflammation. Conditions that can cause inflammation include liver disease, rheumatoid arthritis and other inflammatory conditions, and overactive thyroid, called hyperthyroidism. Rarely, a high ferritin level could be from a condition that causes the body to store too much iron. Some types of cancer also can cause the blood ferritin level to be high.

A ferritin test can diagnose or suggest:

• Iron deficiency anemia.
• A condition that causes the body to absorb too much iron from food, called hemochromatosis.
• Liver disease.
• A rare type of inflammatory arthritis called adult Still disease.

A health care professional might also suggest a ferritin test for people who have a condition that results in too much iron in the body, such as hemochromatosis. Ferritin tests can help watch the condition and guide treatment.

If your blood sample is being tested only for ferritin, you can eat and drink as usual before the test. If your blood sample will be used for other tests, you might need to fast for a time before the test. A member of your health care team will tell you what to do.

During the ferritin test, a member of your health care team puts a needle into a vein in your arm and takes a sample of blood. The blood sample is sent to a lab for study. Most people can go back to your usual activities right away.

The typical range for blood ferritin is:

• For men, 24 to 336 micrograms per liter.
• For women, 11 to 307 micrograms per liter.

Low results

Results that are lower than the typical range show iron deficiency. These results also can mean anemia. If your ferritin level is low, your health care professional will work to find the cause.

Higher than expected results

There can be several causes for a high ferritin level. More testing might be needed to pin down the cause. Causes include:

• Hemochromatosis.
• A group of conditions caused by not having enough of an enzyme that affects the nervous system and skin, called porphyria.
• Rheumatoid arthritis or another ongoing condition that causes swelling, called inflammatory.
• Liver disease.
• Hyperthyroidism.
• Leukemia.
• Hodgkin's lymphoma.
• Repeated blood transfusions.
• Alcohol misuse.
• Taking too many iron supplements.

If you have a high ferritin level, your health care professional might need to look at the results of other tests to figure out next steps.

To learn more about what your ferritin test results mean, talk to your health care professional.