Iron Test

Also known as: Fe; serum iron

Related tests: Ferritin; TIBC and transferrin; haemoglobin; haematocrit

At a Glance

Why Get Tested?

To find out whether your blood iron level is normal

When to Get Tested?

If your doctor thinks that you might have too little or too much iron in your blood. Low iron can cause anaemia, and is usually due to long-term or heavy bleeding, pregnancy, or rapid growth (in children); rarely is it due to poor diet. A high iron level can be due to a genetic condition, extensive blood transfusions, or rarely due to ingestion of an overdose of iron (usually in children).

Sample Required?

A blood sample taken from a vein in your arm

The Test Sample

What is being tested?

Iron is an essential trace element in your blood. It is necessary for forming healthy red blood cells, which carry oxygen through your body, and for some enzymes, which perform tasks in your body.

Because no single test is accepted for diagnosing iron deficiency anaemia (lack of iron), other tests may be requested at the same time, such as TIBC (total iron binding capacity), UIBC (unbound iron biding capacity) or transferrin, and ferritin.

How is the sample collected for testing?

A blood sample is taken by needle from a vein in your arm.

NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.

Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.

The Test

How is it used?

The iron test is used to measure the amount of iron that is carried by transferrin, a protein that transports iron from the intestine to cells that use iron. In people with anaemia, the iron test can help to tell whether it is due to iron deficiency. It can also help to identify when anaemia is due to a long-term (chronic) illness.

The iron test can also be used with the transferrin saturation test to help diagnose hereditary haemochromatosis, a condition where too much iron builds up in the body.

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When is it requested?

Iron tests are not requested routinely. If haemoglobin and haematocrit are abnormal, however, iron tests can be useful to help understand the cause of anaemia. Iron tests can also be used when iron deficiency is being treated to tell if the iron is being absorbed properly and to detect when enough iron has been taken. The test also may be requested when your doctor suspects you may have too much iron. If you have symptoms that could be due to haemochromatosis, iron tests represent the best way to determine whether this could be the diagnosis. In a child who has taken iron tablets, iron levels are the only way to measure the severity of poisoning.

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What does the test result mean?

A low iron is usually due to iron deficiency, especially if transferrin or TIBC is high. With chronic (long-term) diseases, low iron occurs with low transferrin or TIBC.

High levels of serum iron can occur as the result of many blood transfusions, iron injections into muscle, lead poisoning, liver disease, or kidney disease. Haemochromatosis is the most common cause of high iron.

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Is there anything else I should know?

Samples for iron should be taken in the morning, before you have had any food to eat. You should not take any iron pills or tablets for 24 hours before the test. Iron is absorbed rapidly from food or pills, and can make your blood iron levels falsely high.

Substances that can cause high iron levels include the pill, oestrogen pills and preparations, iron supplements, heavy intake of alcoholic drinks, methyldopa, and chloramphenicol.

Substances that can cause your iron level to be decreased include ACTH (a hormone), the drugs colchicine, desferrioxamine, methicillin, and testosterone.

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Common Questions

1. Is iron deficiency the same thing as anaemia? What are the symptoms?

Iron-deficiency anaemia is the most severe form of iron deficiency (low iron levels). Relatively mild iron deficiency, which may cause no effects at all, is referred to as ‘iron depletion’. If a person is otherwise healthy, symptoms seldom appear before the haemoglobin in your blood drops below a certain level (100g per litre). Some signs that your body is low in iron include tiredness and heart palpitations.
As iron levels continue to fall, symptoms can include:

Shortness of breath and dizziness
If the anaemia is severe, angina (chest pain), headache, and leg pains may occur
Children may have learning (cognitive) disabilities
Besides the general symptoms of anaemia, there can be certain symptoms if you have had a long-term case of iron deficiency. These can include a burning sensation in the tongue or a smooth tongue, sores at the corners of the mouth, pica (cravings for specific substances, such as liquorice, chalk, or clay), and spoon-shaped finger- and toe-nails.

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2. Does anaemia due to iron deficiency happen quickly or does it take a long time?

Iron deficiency anaemia comes on gradually. When your rate of iron loss exceeds the amount of iron you absorb from your diet, the first thing that occurs is that iron stores are used up. In this stage, ferritin will be low, but iron and TIBC are usually normal and there is no anaemia. As iron deficiency worsens, blood iron levels fall, TIBC and transferrin rise, and red blood cells may start to become small and pale, but there is still an adequate number of red blood cells. With prolonged or severe iron deficiency, anaemia develops.

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3. What are signs of iron overload in my system?

The most common symptom is pain, as iron accumulates in your body, usually in your . Other symptoms include fatigue and lack of energy, abdominal pain, loss of sex drive, and heart problems. Some people, however, have no symptoms of this condition.

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4. What foods contain the most iron?

If laboratory tests show that you are anaemic, eating the right diet can help. Some good choices for an iron-rich diet include: lean meats, liver, eggs, green leafy vegetables (e.g. spinach, kale), wheat germ, whole grain breads and cereals, raisins, and molasses. If you have been diagnosed as having iron deficiency anaemia, or you are pregnant or breast feeding, iron in the form of vitamin pills or tablets is usually needed to provide the extra iron needed in these states.

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5. My friend told me I can take too much iron—is that right?

Unless you have iron deficiency or eat a very poor diet, you probably don't need extra iron supplements. If you take in much more iron than is recommended, you may develop , which causes a rise in blood iron and ferritin levels. If you have an inherited disorder called haemochromatosis, taking extra iron can cause more rapid iron accumulation and possibly accelerate the rate of damage to your organs.

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NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.