What Are Iron Tests?

What to Expect When Having These Tests

Iron blood tests help your healthcare provider assess whether you have the right amount of iron in your body. If your doctor is concerned that you might have too little or too much iron in your body, you may be advised to have one or more of these tests. This might include tests such as serum ferritin, serum iron, and others.

Purpose of Iron Tests

What Is Iron?

Iron is an important nutrient that your body needs to survive. Among its other functions, iron is an important component of red blood cells, which transport oxygen to all the cells of your body.

Your body can’t make iron for itself, so we need to get enough iron in our diets either through food alone or with the help of additional supplements.

If our iron levels are too low, that can lead to medical problems. On the other hand, if the body has too much iron, that can lead to problems as well. You need to have just the right amount for your body to work the right way.

When Do I Need an Iron Test?

You might need iron tests if your doctor is concerned that you might have too little or too much iron (too much iron is a less common condition). For example, your doctor might order iron studies 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 test shows that you may have a problem with too little iron
  • another test suggests you might have problems with too much iron
  • 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 previously had abnormal iron studies and your doctor wants to monitor you
  • iron overdose is suspected (i.e., accidental overdose in a child or from excess blood transfusions)

The most common reason to have iron tests performed is concern about iron deficiency anemia. This concern might come either from a person’s symptoms or from other test results. 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 this condition. This can cause symptoms like fatigue, dizziness, weakness, and pale skin. One major 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.

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 post-menopausal woman with iron deficiency anemia is more likely to have a serious underlying condition (like cancer leading to blood loss and anemia).

Iron deficiency can also be caused by medical conditions that cause poor absorption of iron, like celiac disease. Iron status can also be important to evaluate in other people with specific risks of iron deficiency, like young infants and the elderly.

People who have a chronic inflammatory disease are also prone to getting a different kind of anemia. Iron tests can help health practitioners tell whether a person has anemia from low levels of iron due to their chronic disease or due to both.

Less commonly, iron studies may be necessary to diagnose or rule out other health conditions. These include:

  • genetic diseases that can cause anemia (such as hemoglobinopathies)
  • genetic diseases that cause too much iron to build up (such as hemochromatosis)
  • lead poisoning

Types of Iron Tests

There are several different tests that can be used to evaluate the status of iron in your body. All of them yield slightly different kinds of information. Your doctor will often have more than one of these performed at the same time from a single blood draw. On the other hand, some of these tests might only be necessary if an earlier test gives a result that is difficult to interpret.

There are many different kinds of iron tests, partly because the movement of iron through the body is quite complex. Most of the iron in your body is bound to different kinds of proteins (because iron that isn’t bound like this can be toxic to cells).

Within your cells, much of the iron is bound to a protein called ferritin. Some of this ferritin is released into the blood. However, most of the iron in the blood is bound to another protein, called transferrin—the main iron transport protein in the blood. Serum iron is another test that represents the amount of iron bound to proteins in the blood (mainly transferrin).

Iron blood tests can only assess iron present in the blood, not the iron stored in the organs like the liver or in your bones.

Some of the possible iron blood tests your doctor might order include:

  • serum ferritin (amount of ferritin in the blood; indirectly measures iron)
  • serum iron (amount of iron that is bound to proteins in the blood)
  • transferrin saturation test or TSAT (percentage of transferrin that is “filled up” with iron)
  • total iron-binding capacity or TIBC: the total amount of iron that could be bound by proteins in the blood
  • transferrin receptor protein test or TRP: these proteins are often measured in people with iron deficiencies

Other more specialized tests may be available as well, depending on the circumstances.

These tests can provide slightly different information to clinicians. For example, serum ferritin is generally considered the single best test to diagnose iron deficiency anemia, which usually shows a lower than normal value. However, it can be falsely elevated in certain circumstances, like inflammation.

Tests like TIBC and TRP can give additional information to help clinicians decided if the anemia is caused by iron deficiency or not.

Risks and Contraindications

There are very few (if any) risks to having iron blood tests. These are basic tests 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, as there might be for any blood sample taken.

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 might interfere with the test results.

Location

You might have your blood taken at a hospital or at an outpatient clinic. In most cases, such tests will be covered by your insurance, but it never hurts to check with your insurer ahead of time. You may need to fill out some paperwork before the test is given.

Food and Drink

In many cases, your healthcare provider may require you to fast before you have your blood draw. This may be particularly the case if you are having any other tests done at the same time as your iron studies.

If so, your health care provider may ask you to not eat or drink anything for 12 hours before the test (often overnight). Water is usually fine. Ask your health care provider if there is anything you need to do in preparation. Your doctor can give you specific instructions if needed.

During the Test

To perform iron blood tests, a healthcare professional needs to take a blood sample. Someone will clean the area. 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 your phlebotomist or nurse finds a good vein to use.

Next, you'll have the needle inserted into a 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, the person taking your blood will put a small bandage on your arm to protect the site of needle insertion. 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.

Interpreting Results

Results are often available within a day or two, but they may take longer if you are having any specialized tests performed. In any case, you’ll need a healthcare professional to help make sense of your results.

Iron studies must always be interpreted in the context of an individual’s overall health picture including their age, sex, pregnancy status, and other potential health conditions.

Iron tests play a role in diagnosis, but they need to be interpreted by someone with expertise and experience. The information you receive will depend on the specific tests performed and also potentially the laboratory where your blood was analyzed.

In some cases, a reference range might be provided along with your test. However, whether or not your value turned up within range might not be a complete indicator of whether a problem is present.

As an example, 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 some sort of other scale might be used, like nanograms per milliliter.

In general, the CDC notes a serum ferritin score lower than 15 micrograms per liter would be a concern for most adults. However, that is not an absolute rule. For example, a serum ferritin score of less than 30 might be a concern in a pregnant woman. That is why it is important to talk with your health care provider about the results of your test in relation to your individual case.

Follow-Up

You will want to discuss your results and what they mean with your healthcare provider. In some cases, the tests were just a precaution, and you will learn that everything is fine. Other times, iron studies might be enough to diagnose you with a health condition. Sometimes, 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 esophagogastroduodenoscopy (EGD). These tests can help identify a potential underlying source of bleeding which might have caused the iron deficiency anemia.

Interpreting the results of iron studies can sometimes be tricky, even for experienced health providers. That is part of why having more than one study can sometimes be helpful. For example, someone iron deficiency will typically (but not always) have low serum ferritin, low serum iron, and high TIBC. However, certain situations might alter your ferritin levels and make them more difficult to interpret. Some of these include:

  • Acute hepatitis
  • Active infections
  • Alcohol abuse
  • Chronic inflammation
  • Certain medications

A person might also have anemia from iron deficiency as well as some anemia from inflammation. In these cases, a test like TRP can sometimes help distinguish whether iron deficiency might be playing a role. A physician might ask that you have a test like this performed if your original iron test or tests gave ambiguous information.

In very rare cases, more invasive tests might be needed to achieve a proper diagnosis, like a bone marrow biopsy.

In general, physicians have more experience and are more comfortable using iron tests to diagnose conditions of iron deficiency. If you are found to have a health condition causing you to have too much iron, you might be referred to a specialist for diagnosis and treatment.

Other Considerations

Iron studies tests aren’t as easy for patients to understand as some other common health tests. 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 health care provider if you 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

It can be hard to wait for lab results such as iron tests. In most cases, however, your healthcare provider will find either that nothing is wrong or that you have a highly treatable condition. Be sure to get these tests if your provider recommends them because sometimes they provide critical information about possible underlying problems. Whatever the outcome, find a healthcare team that will be by your side to help make the best healthcare plan for you. 

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Article Sources
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