If a doctor suspects that a person does not have a healthy amount of iron in their blood, they may order a serum iron test.
In this article, learn more about the uses of a serum iron test. We also explain the normal ranges of iron in the blood and the treatment options for people whose iron levels are too high or too low.
What is a serum iron test?
A serum iron test can determine if a person has abnormally high or low levels of iron in their blood.
A serum iron test provides a way for doctors to determine how much iron is in a person's blood.
The test uses serum, which is the liquid that remains after a doctor removes the clotting elements and blood cells from a blood sample.
The primary purpose of the test is to check whether a person has abnormally high or low levels of iron in their blood, both of which can cause serious health complications.
The results of a serum iron test can help with the diagnosis and treatment of any symptoms that the individual is experiencing. They will typically undergo other types of iron-related serum tests at the same time.
What to expect during the test
The serum iron test is a relatively simple test with minimal risk. In preparation, it may be necessary to fast for up to 12 hours before the test and to avoid taking certain other medications during this time.
A doctor, nurse, or phlebotomist will draw a small sample of blood from the person's arm and send it to a lab for testing. They will then explain the person's results to them in a follow-up appointment before determining the appropriate next steps.
Interpreting the results
The test will measure the total iron level in the serum in micrograms of iron per deciliter of blood (mcg/dL).
In addition to the serum iron test, many people will have a serum transferrin level test. Transferrin is a type of protein that is responsible for transporting iron in the blood.
Transferrin levels can also help a doctor to determine if there is too much or too little iron in the blood. The unit of measurement for transferrin is milligrams per deciliter (mg/dL).
Another common test measures the total iron binding capacity, called TIBC for short, also in mcg/dL. This shows the amount of iron that transferrin can bind to in the blood.
The results can vary over time depending on a person's overall health. Defined normal levels tend to vary from one lab to another but typically fall within the following ranges:
- TIBC: 262–474 mcg/dL
- Total serum iron: 26–170 mcg/dL in women and 76–198 mcg/dL in men
- Transferrin saturation: 204–360 mg/dL
The serum iron test and other related tests may reveal low or high values. Normal ranges can vary, so it is essential for a person to speak to their doctor about what their results mean.
Low iron levels vary between individuals and depend on a person's sex. A score below 26 mcg/dL is outside the normal range for women. For men, a low score is anything below 76 mcg/dL.
An abnormally high iron level would be above 198 mcg/dL for men and over 170 mcg/dL for women.
Causes of abnormal results
A diet low in iron can lead to a deficiency.
Iron levels that are too high or too low may indicate several different health issues.
Low levels could indicate that a person is not consuming enough iron in their diet or that their body is not processing iron correctly.
For women, heavy menstrual cycles may also contribute to lower iron levels.
Other possible causes of low iron levels include:
- blood loss in the gastrointestinal tract
- blood loss from elsewhere in the body
When iron counts are too high, it could indicate that a person is consuming too much iron. High iron levels can also occur if a person has a disease called hereditary hemochromatosis.
Additional causes of high iron counts include:
- chronic liver disease, including liver cirrhosis, liver failure, and hepatitis
- iron poisoning, from taking too many iron supplements
- hemolytic anemia, where the abnormal breakdown of red blood cells depletes their numbers
- multiple packed red blood cell (PRBC) transfusions
How to correct iron levels
Following serum iron and other iron-related tests, a doctor will suggest ways in which a person can correct their iron levels.
People with low levels of iron may need to make changes to their diet or take iron supplements.
They may need to eat more iron-rich foods, which include:
- beef liver
- red meat
- dark green, leafy vegetables
- whole grains
Conversely, those with an elevated iron level should avoid iron in their diet. They may also need to avoid vitamin C supplements, although this is unnecessary in most cases.
If a person has a high iron level as a result of chronic liver disease, they should avoid anything that could hurt the liver more, such as consuming alcohol.
A person with too much iron may also need to undergo a process called phlebotomy, which removes blood from the body.
A doctor will need to run more tests to determine the cause of the iron overload. This will allow them to treat the underlying condition effectively to reduce iron levels.
If a person is experiencing symptoms that indicate too much or too little iron in the blood, a serum iron test can help diagnose the underlying problem.
The serum iron test is a safe and straightforward way to test the level of iron in the blood. While normal ranges can vary between people, a high or low result can help a doctor determine the appropriate treatment.