Serum Iron

Alternate Names
iron level (Fe)

Definition of Serum Iron

A person's blood contains roughly 70% of the total iron in the body. Iron is carried in the hemoglobin of the red blood cells. Hemoglobin is a molecule, part porphyrin and part protein, that is specially equipped to carry oxygen to the cells of the body. Iron from food is absorbed into the plasma through the small intestine. Once in the bloodstream, the iron binds to a blood protein that transports it to the bone marrow. There it is incorporated into the hemoglobin. The serum iron test measures the amount of iron in the plasma that is on its way to the bone marrow.

Who is a candidate for the test?

A serum iron test is done on someone who is suspected either of having too little iron in the blood or an overload of iron in the blood.

How is the test performed?

To measure the serum iron, a blood sample is needed. This is usually taken from a vein on the forearm or hand. First, the skin over the vein is cleaned. Next, a strong rubber tube, or tourniquet, is wrapped around the upper arm. This enlarges the veins in the lower arm by restricting blood flow through them.

A fine needle is gently inserted into the chosen vein, and the tourniquet is removed. Blood flows from the vein through the needle. It is collected in a syringe or vial for testing in the lab. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding .

What is involved in preparation for the test?

The person needs to refrain from eating for 12 hours before the test. Drinking water is permitted.

What do the test results mean?

Normal serum iron levels are:

• Men: 65 to 176µg/dL (micrograms/deciliter)
• Women: 50 to 170 µg/dL
• Newborns: 100 to 250 µg/dL
• Children: 50 to 120 µg/dL

Very high levels of serum iron can indicate a number of conditions. These include:

• hemolytic anemia, which occurs when hemoglobin leaks out of red blood cells
• hemosiderosis or hemochromatosis, which are genetic disorders that cause iron to build up in the body
• iron poisoning, caused by ingestion of too much iron
• a large blood transfusion
• lead poisoning, caused by accidental ingestion of lead
• liver problems, such as hepatitis or cirrhosis

Low serum iron levels may be a sign of:

• chronic blood loss, such as gastrointestinal bleeding
• a diet low in iron
• iron deficiency anemia
• poor absorption of iron from the digestive tract
• third-trimester pregnancy
• tumor growth