Definition A person's blood contains roughly 70% of the total iron in the body. Iron is carried in the haemoglobin of the red blood cells. 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 haemoglobin. 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? This test is done on someone who is suspected of having too little iron in the blood. It is also performed on a person who may have 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 vein chosen 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 laboratory. After the needle is withdrawn, the puncture site is covered for a short time to prevent bleeding .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 176 micrograms/decilitre
Women: 50 to 170 micrograms/dl
Newborns: 100 to 250 micrograms/dl
Children: 50 to 120 micrograms/dl
Very high levels of serum iron can indicate a number of conditions. These include:
iron deposits in the body from excess iron in the bloodstream. The deposits can be caused by genetic condtions known as haemosiderosis or haemochromatosis.
iron poisoning, caused by ingestion of too much iron
leaking of haemoglobin out of the red blood cells, called hemolytic anaemia
Author: Stephanie Slon, BA Reviewer: eknowhow Medical Review Panel Editor: Dr John Hearne Last Updated: 26/05/2005 Contributors Potential conflict of interest information for reviewers available on request
