What Are Iron Tests?

Why They Are Needed and What to Expect

Iron is an essential mineral that your body needs to support numerous functions, including the formation of red blood cells and the production of hemoglobin (a part of red blood cells that transport oxygen through the body). Iron blood tests help assess whether you have the right amount of iron in your body to support these functions.

If your healthcare provider is concerned that you may have too little or too much iron in your body, you may be advised to have one or more iron tests. Some check for iron in the blood, while others check for signs of iron in cells and tissues.

Laboratory with nurse taking a blood sample from patient
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This article looks at different types of iron tests a healthcare provider may order and when and why they are used. It will then walk you through what is involved in the tests, including how the results are interpreted.

Purpose of Iron Tests

Iron is an essential mineral, meaning that your body can't make it. You need to obtain iron from food or, if needed, with iron supplements.

Iron tests measure different substances in the blood to check if iron levels in the body are too high or too low. The tests can also check if you are responding to treatments used to increase or decrease iron levels in the body.

Too Little Iron

Iron tests are often used to check if iron levels are too low, leading to a condition known as iron-deficiency anemia. Anemia is a decrease in the number of red blood cells or the amount of hemoglobin in the blood. With iron-deficiency anemia, anemia is caused by the lack of iron.

There are many reasons why iron-deficiency anemia can occur, including:

Too Much Iron

Having too much iron in the blood is referred to as iron overload. This is a serious condtion in which excess iron is deposited into organs, which may damage organs such as the liver and heart.

Causes of iron overload include:

Other Reasons

Many conditions can mimic the symptoms of iron deficiency anemia and iron overload

Iron tests may be used to rule out other types of anemia, including vitamin deficiency anemia, anemia of inflammation, and aplastic anemia (caused by the failure of the bone marrow).

Iron tests can differentiate iron overload from conditions with similar symptoms, such as fatty liver disease, viral hepatitis, autoimmune hepatitis, and beta thalassemia (a genetic blood disorder).

Recap

Iron tests are used to check whether the iron levels in the body are too high (iron overload) or too low (leading to iron deficiency anemia). They can also rule out conditions with similar symptoms or see if treatments used to treat iron overload or iron deficiency anemia are working.

Types of Iron Tests

There are several different tests used to evaluate the status of iron in your body. All of them yield slightly different pieces of information. Your healthcare provider will often order more than one of these tests from a single blood draw.

The different tests are needed because the movement of iron through the body is complex. Most of the iron in the blood is bound to a protein called transferrin. Within cells, iron is bound to a protein called ferritin, some of which is released into the blood.

There are different tests that reflect these dynamics and help pinpoint the underlying cause of a problem. These include:

  • Serum iron: Used to measure the total amount of iron in the blood
  • Serum ferritin: Used to determine if the total iron content is too low or too high
  • Serum transferrin: Used to measure the amount of transferrin in the blood
  • Total iron-binding capacity (TIBC): Use to show much transferrin is available to carry iron
  • Transferrin saturation test: Used to determine the percentage of transferrin that is “filled up” with iron
  • Transferrin receptor protein (TRP): Used to measure the number of proteins that bind to iron

Based on the findings, the lab can offer explanations as to why iron levels are abnormal. In some cases, a single test, like serum ferritin, can diagnose iron-deficiency anemia.

But more often, a combination of tests is needed. Together, the tests can provide insights that may point the lab in an entirely different direction.

Recap

There are different types of iron tests that yield slightly different pieces of information. Based on the findings of the combined tests, the lab can offer explanations as to why iron levels are either too high or too low.

Risks and Contraindications

There are few, if any, risks associated with iron blood tests. These are basic tests that require a simple blood draw. There may be slight bleeding or bruising at the site of the blood draw. Infection is rare.

If you have a medical condition that interferes with blood clotting, such as hemophilia, talk to your healthcare provider before scheduling the test. You may also be at risk of excess bleeding if you take blood thinners like Coumadin (warfarin) or Plavix (clopidogrel).

Recap

There are few, if any, risks associated with iron blood tests. Slight bleeding or bruising can occur as a result of the blood draw.

Before the Test

Be sure to tell your healthcare provider about all your medications or supplements you take before getting an iron test as some might interfere with the results.

Location

The blood draw may be performed at a hospital, an outpatient clinic, or a health provider's office. In most cases, the tests will be covered by your insurance, but it never hurts to check with your insurer beforehand. You may need to fill out paperwork before the test is given.

Food and Drink

Your healthcare provider may ask you to fast before taking an iron test. If so, you will usually be asked not to eat or drink anything for 12 hours before the test. Water is usually fine.

During the Test

To perform an iron blood test, a healthcare professional needs to take a blood sample. After a vein is selected, usually in the arm, the skin is cleaned with an antiseptic swab. Then, a tourniquet is applied above the site of the blood draw, usually the upper arm.

You may be asked to squeeze your fist while a nurse or a technician called a phlebotomist inserts a needle into the vein. This usually only hurts for a moment. It shouldn’t take more than a few minutes for the sample to be taken.

After the Test

After your sample is taken, a small bandage is applied to the wound. You will usually be able to return to your normal activities right away.

If you feel 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. 

Recap

Iron tests involve a simple blood draw. You will typically be asked to fast for 12 hours beforehand. Tell your healthcare provider about any medications or supplements you take as some can interfere with the results.

Interpreting Results

The results of iron blood tests are usually available within a day or two but may take longer if other blood tests are performed.

Iron studies need to be interpreted in the context of a person's overall health, including their age, sex, medical history, pregnancy status, and other health conditions they may have.

Follow-Up

You will want to discuss the results of the tests with your healthcare provider to understand what they mean. In some cases, the tests are performed as a precaution, and you will be told that everything is fine.

At other times, the tests may be enough to diagnose a health condition and prescribe immediate treatment. At other times still, further investigation will be needed before treatment can be prescribed.

For example, if diagnosed with iron deficiency anemia, your healthcare provider may go ahead and prescribe iron supplements to get your iron levels back up. This is typically the case if you have risk factors for iron deficiency anemia—such as being a vegetarian on a low-iron diet—and there are no concerning symptoms other than, say, fatigue.

If the cause of iron deficiency anemia is unclear, other tests may be ordered. This may involve tests to check for gastrointestinal bleeding, such as stool tests or endoscopy (the insertion of a flexible fiberoptic scope into the mouth or rectum). Blood tests can be used to check for celiac disease, while an examination of your stool may reveal the presence of parasitic worms.

Similarly, if there is iron overload, your healthcare provider may order genetic tests and a liver biopsy (the extraction of a liver tissue sample) if hemochromatosis is suspected. This is particularly true if there is a family history of the disease.

Recap

In some cases, iron tests alone can diagnose iron deficiency anemia or iron overload. But oftentimes, additional tests are needed to identify the underlying cause.

Summary

Iron tests are a panel of different tests used to check the iron levels in your blood. Having too little or too much iron can cause health problems.

Iron tests can help diagnose iron deficiency anemia caused by the lack of iron in the blood. They also detect iron overload in which too much iron can accumulate in organs and cause damage.

Iron tests involve a simple blood draw after a period of fasting. Based on the evaluation of the different tests—some of which check for iron in the blood and others of which check for iron in tissues and cells—the lab can offer explanations as to why iron levels are abnormal.

A Word From Verywell

Interpreting the results of iron studies can be tricky, even for experienced health providers. That is why you shouldn't assume the worst if one or even several test results are abnormal. It is important to have patience and to ask as many questions as you need to understand why tests are being performed and what they mean.

It is also a good idea to keep a copy of your lab results. This provides you with a point of comparison if further testing is needed.

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6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  2. MedlinePlus. Iron tests.

  3. MedlinePlus. Iron deficiency anemia.

  4. McDowell LA, Sticco KL. Iron overload. In: StatPearls [Internet]. Treasure Island FL: StatPearls Publishing; 2022.

  5. Daru J, Allotey J, Peña-Rosas JP, Khan KS. Serum ferritin thresholds for the diagnosis of iron deficiency in pregnancy: a systematic review. Transfus Med. 2017;27(3):167-74. doi:10.1111/tme.12408

  6. Ramanathan G, Olynyk JK, Ferrari P. Diagnosing and preventing iron overload. Hemodial Int. 2017 Jun;21 Suppl 1:S58-S67. doi:10.1111/hdi.12555

Additional Reading
  • Iron Tests. American Association for Clinical Chemistry.

  • Adamson JW. Iron Deficiency and Other Hypoproliferative Anemias. In: Longo DL, Fauci AS, Kasper DL, et al, eds. Harrison’s Principles of Internal Medicine.18th ed. New York, NY: McGraw Hill; 2011: 844-851.

  • 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

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

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