As its name suggests, a serum iron test measures how much iron is in your serum. Serum is the liquid that is left over from your blood plasma when the red blood cells and the clotting elements have been removed. This test can help your doctor figure out if there is a problem with your iron levels.
Especially high or low iron levels can cause a variety of vague symptoms, such as fatigue, weakness, difficulty concentrating, and moodiness. The serum iron test can reveal both unusually low and abnormally high blood iron levels.
A nurse will insert a needle into a vein in your arm or hand and draw a small sample of blood. This sample will then be tested in a laboratory.
Your doctor may ask you to fast beginning at midnight the night before the procedure. The morning is the best time to conduct this test because that’s when your iron levels are highest.
Serum iron is not a routine test. It is usually ordered as a follow-up after an abnormal result on a more common test, such as a complete blood count or hemoglobin test.
Your doctor may also order a serum iron test if he or she suspects that your iron levels are abnormal because you are exhibiting symptoms of anemia. If your iron levels are abnormal, you may either have iron deficiency or iron overload.
Early symptoms of iron deficiency (anemia) include:
- chronic fatigue
- muscle weakness
As your condition worsens, you may develop other symptoms, including:
- difficulty concentrating
- tongue and mouth sores
- pica (the compulsion to eat non-food items, such as paper or ice chips)
- misshapen nails
Symptoms of iron overload (when your body produces too much iron) include:
- pain in your abdomen and joints
- bronzing/darkening of skin
- heart problems
- lack of energy
- lack of sex drive
- weight loss
- muscle weakness
These symptoms generally worsen as your condition progresses.
Serum iron is measured in micrograms of iron per deciliter of blood (mcg/dL). The National Institutes of Health (NIH) reports that the following ranges are “normal” for a serum iron test: (NIH, 2012)
- iron: 60 to 170 mcg/dL
- transferrin saturation: 20 percent to 50 percent
- TIBC (total iron binding capacity): 240 to 450 mcg/dL
Abnormally high iron serum levels may mean that you have consumed too much iron, vitamin B-6, or vitamin B-12. In some cases, high iron levels can indicate:
- hemolytic anemia or hemolysis (when your body does not have enough healthy red blood cells)
- liver conditions, such as hepatic necrosis and hepatitis
- iron poisoning (when you’ve taken more than the recommended dose of iron supplements)
- iron overload (when your body naturally retains too much iron)
Abnormally low iron levels may mean that you have not consumed enough iron or that your body is not absorbing the iron properly. Regularly having heavy menstrual periods can also lead to low iron levels. In other cases, low iron levels can indicate:
- gastrointestinal blood loss
If your levels are low and your doctor tells you to eat a diet rich in iron, choose foods with high iron content, such as:
- red meats
- leafy, dark green vegetables
Many medications can affect the results of a serum iron test by increasing or decreasing your iron levels. Some, such as birth control pills, are very common. Tell your doctor before the test if you are taking any medications.
Your doctor may instruct you to temporarily stop taking those medicines that will affect the test. If you cannot stop taking the medication, your doctor will take the medication’s effects into account when interpreting your results.
You will probably experience mild pain or a pricking sensation when you have your blood drawn. You might also bleed a little afterward or develop a small bruise at the puncture site. In rare cases, you might experience more serious complications, such as an infection, excessive bleeding, or fainting.