What are iron tests?

Iron tests measure different substances in the blood to check iron levels in your body. Iron is a mineral that your body needs for growth and development. Your body uses iron to make hemoglobin, a protein in red blood cells. It carries oxygen from the lungs to all parts of the body, Iron is also important for healthy muscles, bone marrow, and organ function. Your body also needs iron to make some hormones.

You get iron from eating food or taking supplements. There are iron-only supplements, but many multivitamin/mineral supplements also contain iron.

Most people in the United States get enough iron. However, certain people may be more likely to have trouble getting enough iron. For example, those who:

• Have heavy periods
• Are pregnant or breastfeeding
• Are infants (especially if they are premature or low birth weight)
• Are frequent blood donors
• Have cancer, certain digestive diseases, or heart failure

The amount of iron you need each day depends on your age, your sex, and whether you consume a mostly plant-based diet. Iron levels that are too low or too high can cause health concerns. For example, not having enough iron in your body is the most common cause of anemia. Anemia is a condition in which your blood has a lower-than-normal amount of red blood cells.

The amount of iron in your blood varies throughout the day and may be higher in the morning.

There are different types of iron tests. You may just have one type of test. But in some cases, your health care provider might order several different iron tests to understand your results better. The different types of iron tests include:

• Serum iron test, which measures the amount of iron in the blood
• Transferrin test, which measures transferrin, a protein that moves iron throughout the body
• Total iron-binding capacity (TIBC), which measures how well iron attaches to transferrin and other proteins in the blood
• Ferritin blood test, which measures how much iron is stored in the body

Other names: Serum Iron, Serum Fe, Ferritin Test, Serum Ferritin

What are they used for?

Iron tests are most often used to:

• Check if the iron levels in your blood are too low, a sign of anemia. But not all people who have low iron levels have anemia.
• Diagnose different types of anemia.
• Check if the iron levels in your blood are too high, which could be a sign of hemochromatosis (also called iron overload). This condition causes too much iron to build up in your body. It can be inherited (passed down through families) or be caused by another health condition.
• Measure the amount of iron stored in your liver to check for liver disease.
• Check for restless legs syndrome (tingling or burning feelings in your legs).
• Check for adult Still disease, also called adult-onset Still disease or AOSD. This is not a common condition. Symptoms include a high ferritin level, joint pain, fever, and a rash.
• See if treatments for iron deficiency (low iron levels) or excess iron (high iron levels) are working.

Why do I need an iron test?

You may need testing if you have symptoms of iron levels that are too low or too high. However, low iron may not cause symptoms until the level is very low. So, your provider may order a routine iron test to check your iron level.

Symptoms of iron levels that are too low include:

• Weakness or fatigue
• Dizziness
• Shortness of breath
• Arrhythmia (a problem with the rate or rhythm of your heartbeat)

Symptoms of iron levels that are too high include:

• Weakness or fatigue
• Joint pain, most often in the knees or hands
• Abdominal (belly) pain
• Loss of interest in sex or erectile dysfunction (ED)
• Changes in skin color, which may look gray, metallic, or bronze

What happens during an iron test?

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

Will I need to do anything to prepare for the test?

Your provider may ask you to fast (not eat or drink) for 12 hours before your test. The test is usually done in the morning. If you have any questions about how to prepare for your test, talk to your health care provider.

Are there any risks to iron tests?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

What do the results mean?

To understand the results of your iron test, your provider will consider your symptoms, age, medical history, and the results of other blood tests.

If one or more iron test results show your iron levels are too low, it may mean you have:

• Iron deficiency anemia, a common type of anemia.
• Another type of anemia.
• Thalassemia, a blood disorder that is inherited (passed down through families). It causes the body to make fewer than normal healthy red blood cells.

If one or more iron test results show your iron levels are too high, it may mean you have:

• Hemochromatosis
• Lead poisoning
• Liver disease

Most conditions that cause too little or too much iron can be treated with iron supplements (for low iron), changes to your diet, medicines, and/or other therapies.

If your iron test results are not normal, it does not necessarily mean you have a medical condition that needs treatment. Some medicines, including birth control pills and estrogen treatments, can affect iron levels. Iron levels may also be lower for women during their menstrual cycles.

If you have questions about your results, talk to your provider.

Learn more about laboratory tests, reference ranges, and understanding results.

Is there anything else I need to know about iron tests?

Your provider may order other blood tests to help check your iron levels. These include:

• Hemoglobin test
• Hematocrit test
• Complete blood count
• Mean corpuscular volume