What Is Serum Ferritin?

What to expect before, during, and after this test

A serum ferritin test measures the amount of ferritin in your blood. This blood test indirectly provides information about whether there is too much or too little iron available in your body.

Also known simply as a "ferritin test" or a "serum ferritin level," the test has been available since the 1970s. It is a test commonly used to check for possible iron-deficiency anemia.

Why might I need a serum ferritin test?
Illustration by Brianna Gilmartin, Verywell 

Purpose of a Serum Ferritin Test

What Is Ferritin?

A serum ferritin test measures the amount of ferritin in your blood. Ferritin is a type of protein that binds iron and stores it inside your cells. Some ferritin is also present in the bloodstream, where it also binds iron and delivers it to some cells that need it. The ferritin in your body also plays important roles in inflammation and immunity in your body.

Although serum ferritin is a blood test, it indirectly checks for the amount of iron stored inside your body as a whole.

Having the right amount of iron in your body is important because iron is essential for many bodily processes. It is particularly important for the health of red blood cells, which bring oxygen to the cells of your body. Your body can’t make iron on its own, so ferritin stores are reflective of how much iron a person has been getting through their diet (and potentially through supplements).

If a person has lost red blood cells through blood loss, that may also show up as a low ferritin level.

Why Might I Need a Serum Ferritin Test?

A ferritin test is often ordered when a health practitioner is concerned that a person has too little iron in their blood. Less commonly, it might be ordered when there is a suspicion that a person might have too much iron. Having either too much or too little iron in your blood can lead to health problems.

For example, your healthcare provider might suggest a serum ferritin test if:

  • your symptoms or medical history suggest you might have too little iron
  • your symptoms or medical history suggest you might have too much iron
  • another blood test shows that you may have a problem with too little iron
  • another test suggests you might have problems with too much iron (less common)
  • you have another medical condition that puts you at risk of iron deficiency (such as chronic kidney disease)
  • something else about your situation puts you at risk of iron problems (i.e., pregnancy)
  • a previous iron test revealed results that were difficult to interpret
  • you’ve had abnormal serum ferritin in the past, and your doctor wants to monitor you
  • there is a concern for iron overdose (i.e., accidental overdose in a child or overload from excess blood transfusions)

The most common reason for a serum ferritin test is due to concern for iron-deficiency anemia. In fact, it is the best single iron test that can be used to diagnose that condition.

Anemia is a medical condition in which a person has a reduced number of properly working red blood cells. Since iron is needed for your red blood cells to be healthy, not having enough iron can lead to the condition. This can cause symptoms like fatigue, dizziness, weakness, and pale skin.

One main test which might indicate iron deficiency anemia is a CBC (complete blood count). This might show lower than normal hemoglobin, hematocrit, and smaller than normal red blood cells. Often, however, an iron test like serum ferritin is needed to confirm this.

A person might not have enough iron in their blood for a number of different reasons. For example, this might happen because:

  • a person isn’t getting enough iron through diet or supplements
  • iron needs have increased (i.e., due to pregnancy)
  • a woman is losing excess iron through heavy menstrual periods
  • a person is experiencing chronic blood loss (e.g., from colon cancer)
  • a person is unable to absorb iron adequately (e.g., due to celiac disease)

Women are more likely to have iron deficiency anemia than men, partly because of blood loss through menstruation. However, it can be important to investigate for iron deficiency anemia in men as well. A man or menopausal woman with iron deficiency anemia is more likely to have a serious underlying condition.

Iron status can also be important to evaluate in other people with specific risks of iron deficiency, like young infants and the elderly.

Less commonly, serum ferritin might be used to help diagnose or rule out other conditions, such as:

  • anemia from inflammation
  • genetic diseases that can cause anemia (like hemoglobinopathies)
  • genetic diseases that cause too much iron to build up (i.e., hemochromatosis)
  • lead poisoning

Other tests

A serum ferritin test is sometimes given by itself, but often it is given at the same time as one or more other iron tests. In other words, it is usually most easily interpreted in the context of other iron tests, and sometimes other blood tests as well. These iron tests might include:

  • serum iron test
  • transferrin test
  • total iron binding capacity (TIBC)
  • transferrin saturation (TSAT)
  • transferrin receptor protein test (TRP)

These other tests give slightly different kinds of information than the ferritin test. For example, a serum iron test tells how much iron is present inside your blood (either bound to ferritin or to another protein called transferrin). The physiology of iron in the body is quite complicated, and interpretation of these iron tests is sophisticated.

It is by combining the information from more than one of these tests that health care providers can often give the best information about whether your iron is normal and an explanation as to why.

Risks and Contraindications

There are very few (if any) risks to having a serum ferritin test. It is a basic blood test that can be assessed as part of a simple blood draw. Sometimes there is slight bleeding or bruising at the site of the blood draw.

If you have a medical condition that makes your blood clot less easily, talk to your doctor before scheduling the test. You may also have a greater risk of excess bleeding if you take certain medications, like warfarin or other blood thinners.

Before the Test

Make sure your healthcare provider knows about all your medications and supplements before you get your test, as some of these may interfere with the test results.

In many cases, your healthcare provider may require you to fast before you have your blood draw. This may be especially true if you are having any other tests done at the same time as your ferritin test. If so, your healthcare provider may ask you not to eat or drink anything for 12 hours before the test (often overnight).

Usually, water by itself is okay. Ask your healthcare provider if there is anything specific you need to do in preparation. Your doctor can give you specific instructions if needed.

During the Test

To perform the ferritin test, a health care professional needs to take a blood sample. Someone will clean the area. Next, a tourniquet will be applied above the region of the vein to be used, usually the upper arm. You may be asked to squeeze your fist while your phlebotomist or nurse finds a good vein to use.

The needle will be inserted into a vein in your arm. This usually only hurts for a moment or two. A small band-aid can be applied after the blood draw is complete.

After the Test

In almost all cases, you will be able to return to your normal activities right away. If you are dizzy after the blood draw, you may need to sit for a while or have something to eat or drink before going about the rest of your day. The sample is promptly sent to a medical laboratory for analysis. Results are often available within a day or two.

Interpreting Results

Typical Serum Ferritin Values

Serum ferritin results are typically given in terms of a blood concentration, showing how much ferritin is present in a certain volume of blood. Often this is provided as micrograms per liter, but another scale might be used, like nanograms per milliliter. (These two scales provide the same number.)

You’ll need help from your physician to interpret these results (which will usually be given along with other iron tests). But in general, the test may indicate whether your serum ferritin (SF) is within a normal range for your age, gender, and pregnancy status. Women tend to have lower SF values than men. Roughly speaking, 30 to 300 is considered a normal SF for men, and 10 to 200 is considered normal for women.

For example, your health care provider might be worried about iron deficiency anemia in a child less than five years old who has an SF of less than 12. For pregnant women, there might be a concern if the SF is less than 30. In general, the CDC notes that a SF lower than 15 micrograms per liter would be a concern for most adults. However, that is not an absolute rule. That is why it is important to talk with your health care provider about the results of your test.

Low vs. High Ferritin

Low ferritin is a very good indicator that a person has iron deficiency anemia. However, hypothyroidism can also be a source of low levels. Also, you might still have iron deficiency anemia even if your ferritin comes back normal.

In general, many physicians are more familiar with using ferritin as a marker of iron depletion as opposed to iron excess. If your ferritin comes back high, you might be referred to a specialist for diagnosis and workup, depending on the context. Elevated ferritin is sometimes found in Hodgkin’s disease, acute leukemia, and in many other cancers.

However, it is important to note that high ferritin isn’t a diagnostic marker for these diseases; it's just something that might sometimes be seen with them. Certain rare genetic diseases can cause elevated ferritin as well. Still’s disease and hemophagocytic syndrome are two other rare conditions that often display elevated ferritin.

Follow-Up

You’ll want to discuss your results and what they mean with your healthcare provider. In some cases, the tests may simply be a precaution. Other times, iron studies might be enough to diagnose you with a health condition. In other situations, further investigations might be needed.

For example, you might be diagnosed with iron deficiency anemia. If a plausible cause for this is present, your doctor may prescribe iron supplements to help get your iron up to normal levels. You might need later follow-up iron studies to make sure your levels had become normal.

If you are found to have iron deficiency anemia but a cause isn’t obvious, you may need other tests or studies. For example, men or postmenopausal women with iron-deficiency anemia usually need other tests, like a colonoscopy and potentially an esophagogastroduodenoscopy (EGD). These tests can help identify a potential underlying source of bleeding which might have caused the iron deficiency anemia.

Some conditions may increase your ferritin levels and make them more difficult to interpret. Some of these include:

In this case, you might need additional iron tests or other laboratory tests to get more clarity about your condition. 

Other Considerations

You shouldn’t assume that you have a problem if your test results come back marked as abnormal. In some cases, everything may be fine. Sometimes there are laboratory errors, and other times you might have a value outside the typical range for a good reason.

On the other hand, be sure to go ahead and discuss your results with a healthcare provider if you still have concerns. As always, a dialogue with your physician is warranted. It is also a good idea to keep a copy of all your old records. That way, you will have a point of comparison if further testing is needed.

A Word From Verywell

Waiting for test results can be anxiety-provoking, even for a simple test like serum ferritin. Fortunately, most of the time your healthcare provider will find either that nothing is wrong or that you have a highly treatable condition. However, sometimes serum ferritin can provide a critical about serious underlying problems. Getting the information you need will help increase your own sense of reassurance and control.

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Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Association for Clinical Chemistry, Ferritin

  2. UCSF Medical Center, Medical Tests: Ferritin

  3. Daru J, Colman K, Stanworth SJ, et al. Serum ferritin as an indicator of iron status: what do we need to know? Am J Clin Nutr. 2017;106(Suppl 6):1634S-1639S. DOI: 10.3945/ajcn.117.155960.

  4. Wang W, Knovich MA, Coffman LG, et al. Serum ferritin: past, present and future. Biochim Biophys Acta. 2010;1800(8):760-9. DOI:10.1016/j.bbagen.2010.03.011.

Additional Reading

  • Halland M, de Malmanche J. Interpretation of iron studies: a practical approach. Medicine Today. 2011; 12(7) 65-66.