Also known as: Serum iron
Name: Serum iron
Related tests: Ferritin , Haematocrit , Haemoglobin, Haemoglobin variants, TIBC, Transferrin, ZPP
Why is it measured?
To determine whether the level of iron in the blood is normal
When is it measured?
When the doctor thinks the patient’s blood iron levels may be too high or too low. Low iron levels can cause anaemia and are usually due to heavy or prolonged bleeding, pregnancy or rapid growth (in children), and only rarely to a poor diet. High iron levels may be due to a genetic disease, multiple transfusions or, rarely, taking an excessive dose of iron (usually in children).
What type of sample is required?
A blood sample taken from a vein in the arm.
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.
Because a single test is not enough to diagnose iron deficiency, iron is usually measured together with other tests. Iron is generally measured together with TIBC (total iron-binding capacity), except when iron poisoning is suspected.
How is the sample collected?
The sample is taken by inserting a needle into 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.
Direct iron measurement, together with the transferrin saturation test, can be used as a screening test for hereditary haemochromatosis. The College of American Pathologists recommends haemochromatosis screening for everyone over the age of 20, because of the low cost of diagnosis and treatment when the condition is diagnosed early. Other organisations do not yet recommend screening, as it is not yet possible to tell 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 iron measured?
This test is not normally requested. 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 the treatment is working and to decide when to stop it. The doctor may also request this test if iron levels are suspected to be too high. When there are symptoms that could be due to haemochromatosis, iron studies 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 can differ between laboratories because they depend on many factors, including the patient’s age, sex, the reference population and the analytical methods. Your laboratory report should include specific reference ranges for each test. Lab Tests Online strongly recommends always discussing your test results with your doctor. For more information on reference ranges, we suggest reading the article “Reference ranges and what they mean”.
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 may occur with multiple 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, meticillin 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 period?
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, prolonged iron deficiency can cause symptoms that may include a burning sensation on 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 overload in the body?
The most common symptom is pain, usually in the joints. Other symptoms include tiredness, lack of energy, abdominal pain, loss of sex drive and heart problems. Some people, however, 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. Are they right?
If you do not 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 causes raised iron and ferritin levels in the blood. If you have a genetic predisposition to haemochromatosis, taking more iron can cause it to build up quickly 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 iron absorption in the intestine, the first thing that happens is that the body’s stores are used up. At this stage, ferritin is low, but iron and TIBC levels are usually normal and there is no anaemia. If the iron deficiency gets worse, serum iron levels fall, TIBC and transferrin rise, and the red blood cells start to become smaller and paler while still being present in adequate numbers. With severe or prolonged iron deficiency, anaemia develops.