Ferritin Blood Test

Medically Reviewed by Carol DerSarkissian, MD on September 10, 2022

What Is a Ferritin Blood Test?

A ferritin test measures the amount of a blood protein called ferritin, which stores iron. Think of your body as a kitchen pantry. Most of it is stocked with food you use every day. But you keep some items in there long-term -- an extra box of pasta or can of beans to have on hand when supplies get low.

Your body stores iron the same way. It uses some of the iron it gets from food right away to make oxygen in your blood. But it also keeps some iron on hand for times when you aren’t getting enough from the food you eat.

The iron is stored in a protein called ferritin. To see how much is in your body, your doctor might order a ferritin blood test.

Why Do I Need a Ferritin Blood Test?

Doctors order a ferritin test if other blood tests point to possible anemia, which can lead to a lack of oxygen in your blood. It can show if there is too much or too little iron in your body. Doctors can also use it to diagnose restless legs syndrome and Still's disease in adults (a rare type of arthritis with fever and rash).

Low iron could be the cause if you:

Often feel dizzy, weak, and tired
Have headaches
Look pale
Are short of breath
Have a rapid heartbeat

You may also have strange cravings for licorice, chalk, dirt, or clay. You may feel a burning sensation on your tongue.

If left unchecked, low levels of iron can cause heart failure (when your heart doesn’t pump blood to your body as well as it should). It can also cause these symptoms:

A ferritin blood test can also help your doctor figure out whether your body is storing too much iron. High levels may point to alcohol abuse, infection, liver disease, rheumatoid arthritis, overactive thyroid, or some types of cancer.

Symptoms of high iron levels vary and can include:

Exhaustion
Heart problems
Joint pain
Low sex drive
Loss of body hair
Stomach pain
Weight loss
Abdominal pain
Lack of energy

How Do I Prepare for a Ferritin Blood Test?

If ferritin is the only test you're having, you can eat and drink as usual. You may need to fast for other blood tests. Always check with your doctor beforehand.

Think about wearing a shirt with short sleeves so the lab technician can get to your arm easily.

How Is a Ferritin Blood Test Performed?

A ferritin test should only take a few minutes. Remember to look away if the sight of blood or a needle makes you dizzy or nauseated.

After cleaning the skin around it, a technician will insert a needle into a vein in your arm. They may wrap an elastic band around the upper part of your arm to make the vein easier to find. Once they’ve collected the right amount of blood, the technician will remove the band and needle and stop the bleeding with a cotton ball or bandage. They’ll label the blood and send it to a lab.