Iron

What is being measured?
The test measures the concentration of iron in the blood. Iron is a trace element needed to produce normal red blood cells (which carry oxygen around the body) and some enzymes that carry out various functions in the body.

Since a single test is not enough to diagnose iron deficiency, iron is generally measured together with other tests. It is usually combined with TIBC (total iron-binding capacity), except when iron poisoning is suspected.

How is the sample collected?
The sample is taken with a needle from a vein in the arm

How is the iron test used?
When is the iron test requested?
What does the test result mean?
Is there anything else I should know?

How is the iron test used?
The iron test is used to measure the amount of iron carried by transferrin, which transports it from the gut to the cells that use it. In people with anaemia, the iron test can help show whether it is due to iron deficiency or to a chronic disease.

Serum iron, together with transferrin saturation, can be used as a screening test for hereditary haemochromatosis. The College of American Pathologists recommends screening for haemochromatosis for everyone over 20, because diagnosis and treatment are inexpensive when the condition is diagnosed early. Other organisations do not yet recommend screening, as it is not yet possible to say whether a person with genetic abnormalities will ever develop symptoms and organ damage. Various studies are trying to develop a strategy for deciding when and how to screen the population.

When is the iron test requested?
This test is not normally requested routinely. However, if haemoglobin and haematocrit are abnormal, it can help determine the cause of the anaemia. Iron may also be measured during treatment for iron deficiency, to see whether treatment is working and to decide when to stop it. The doctor may also request this test if iron is suspected to be too high. When there are symptoms that could be due to haemochromatosis, tests of iron metabolism are the best way to confirm the diagnosis. Measuring iron is the only way to determine how severe the poisoning is when a child has swallowed iron tablets.

What does the test result mean?
There is no single reference range for this test. Reference values may differ between laboratories, as they depend on many factors, including the patient’s age and sex, the reference population and the analytical methods.

A low iron level is generally due to deficiency, especially if transferrin or TIBC is high. In chronic diseases, low iron levels are associated with low transferrin or TIBC.

High iron levels can occur with many blood transfusions, intramuscular iron injections, lead poisoning and liver or kidney disease. Haemochromatosis is the main cause of high iron levels.

Is there anything else I should know?
The blood sample for iron should be taken in the morning on an empty stomach. Do not take iron tablets in the 24 hours before the test. Iron is absorbed quickly from food or tablets and could give a falsely high result.

Contraceptive pills, oestrogen pills and preparations, iron supplements, heavy drinking, methyldopa and chloramphenicol can raise iron levels.

ACTH (a hormone), colchicine, deferoxamine, methicillin and testosterone can lower iron levels

1. Is iron deficiency the same as anaemia? What are the symptoms?
2. What are the signs of iron build-up in the body?
3. Which foods contain the most iron?
4. My friends tell me I should take more iron. Is that right?
5. Does iron deficiency anaemia develop quickly or over a long time?

1. Is iron deficiency the same as anaemia? What are the symptoms?
Iron deficiency anaemia is the most serious form of iron deficiency. Mild iron deficiency may have no effect at all. In an otherwise healthy person, symptoms rarely appear before haemoglobin falls below a certain value (10 g per decilitre). Tiredness and palpitations may be symptoms of iron deficiency.

If iron levels continue to fall, there may be:

• Shortness of breath and dizziness
• If the anaemia is severe, angina (chest pain), headache and leg pain
• Children may have learning difficulties.
• As well as the symptoms of anaemia, long-term iron deficiency can cause symptoms including a burning sensation in the tongue, sores at the corners of the mouth, pica (cravings for substances such as liquorice, chalk or clay) and spoon-shaped fingernails and toenails.

2. What are the signs of iron build-up in the body?
The most common symptom is pain, usually in the joints. Other symptoms are tiredness, lack of energy, abdominal pain, loss of sex drive and heart problems. However, some people have no symptoms.

3. Which foods contain the most iron?
If blood tests show anaemia, a proper diet can help. An iron-rich diet includes lean meat, liver, eggs, green leafy vegetables (spinach, kale, cabbage), wheat germ, wholemeal bread and cereals, raisins and molasses. In iron deficiency anaemia, pregnancy or breastfeeding, iron tablets are usually needed. Your doctor will be able to recommend the most suitable supplement.

4. My friends tell me I should take more iron. Is that right?
Unless you have iron deficiency or a very poor diet, you probably do not need to take an iron supplement. Taking too much iron can lead to haemosiderosis, which raises iron and ferritin in the blood. If you have a genetic predisposition to haemochromatosis, taking more iron can lead to its rapid build-up and speed up possible organ damage.

5. Does iron deficiency anaemia develop quickly or over a long time?
Iron deficiency anaemia develops gradually. When iron loss exceeds absorption from the gut, the first thing that happens is that the reserves are used. At this stage ferritin is low, but iron and TIBC are generally normal and there is no anaemia. If the iron deficiency gets worse, serum iron falls, TIBC and transferrin rise, and the red blood cells start to become smaller and paler, although still adequate in number. With severe or prolonged iron deficiency, anaemia develops