A serum iron test measures how much iron is in your serum. Serum is the liquid that is left over from your blood when red blood cells and clotting factors have been removed.
The serum iron test can reveal abnormally low or high blood iron levels. Your doctor will most likely order this test after another lab test shows an abnormal result.
Having too much iron — or not enough — can cause serious health problems. This test will help your doctor give you a more accurate diagnosis.
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. Morning is the best time to conduct this test because that’s when your iron levels are highest.
Your doctor may also order a serum iron test if you’re showing symptoms of anemia. Abnormal iron tests could be a sign of iron deficiency or iron overload.
Early symptoms of iron deficiency (anemia) include:
- chronic fatigue
- muscle weakness
You may develop other symptoms as your condition worsens. These may include:
- 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 or darkening of skin
- heart problems
- lack of energy
- lack of sex drive
- weight loss
- muscle weakness
These symptoms generally get worse as your condition progresses.
Serum iron is measured in micrograms of iron per deciliter of blood (mcg/dL). The following are considered normal ranges for a serum iron test:
- iron: 60 to 170 mcg/dL
- transferrin saturation: 25 percent to 35 percent
- Total iron binding capacity (TIBC): 240 to 450 mcg/dL
Transferrin is a protein in the blood that transports iron throughout your body. Examining how much iron is in the transferrin proteins can tell your doctor if you have too much or too little iron in your blood.
TIBC measures how well the transferrin proteins are transporting iron around your body.
Abnormally high iron serum levels may mean you’ve consumed too much iron, vitamin B-6, or vitamin B-12. High levels of iron may indicate:
- hemolytic anemia or hemolysis: your body doesn’t have enough healthy red blood cells
- liver conditions: such as hepatic necrosis (liver failure) and hepatitis
- iron poisoning: you’ve taken more than the recommended dose of iron supplements
- iron overload: your body naturally retains too much iron
Abnormally low iron levels may mean you haven’t consumed enough iron or your body isn’t absorbing the iron properly. Regularly having heavy menstrual periods can also lead to low iron levels.
Low iron levels may also indicate:
- gastrointestinal blood loss
Impact of Medications
Many medications can affect the results of a serum iron test by increasing or decreasing your iron levels. For example, birth control pills are commonly used and can affect iron levels. Tell your doctor before the test if you’re taking any medications.
Your doctor may instruct you to temporarily stop taking medicines that will affect the test. If you can’t stop taking the medication, your doctor will take the medication’s effects into account when interpreting your results.
You’ll probably experience mild pain or a pricking sensation when you have your blood drawn. You might also bleed slightly afterward or develop a small bruise at the puncture site.
In rare cases, you might experience more serious complications, such as:
- excessive bleeding
Your doctor will review your results with you. They may suggest iron supplements or diet changes, depending on the levels of iron in your blood.
Your doctor may suggest eating more iron-rich foods if your iron levels are too low. Iron-rich foods include:
- red meats
- leafy, dark green vegetables
More tests may be needed before your doctor can diagnose you with a health condition.