test checks the amount of iron in the blood to see how well iron is
metabolized in the body. Iron (Fe) is a mineral needed
hemoglobin, the protein in red blood cells that
carries oxygen. Iron is also needed for energy, good muscle and organ
About 70% of the body's iron is bound to hemoglobin in
red blood cells. The rest is bound to other proteins
(transferrin in blood or ferritin in bone marrow) or stored in other body
tissues. When red blood cells die, their iron is released and carried by
transferrin to the bone marrow and to other organs such as the liver and
spleen. In the bone marrow, iron is stored and used as needed to make new red
The source of all the body's iron is food, such as
liver and other meat, eggs, fish, and leafy green vegetables. The body needs
more iron at times of growth (such as during adolescence), for pregnancy,
during breast-feeding, or at times when there are low levels of iron in the
body (such as after bleeding).
Healthy adult men get enough iron
from the food they eat. Men have enough reserves of iron in their bodies to
last for several years, even if they take in no new iron. Men rarely develop an
iron deficiency because of their diets. But women can lose large amounts of
iron because of menstrual bleeding, during pregnancy, or while breast-feeding.
So women are more likely than men to develop an iron deficiency and may need to
take an iron supplement. Iron deficiency in men and in women past menopause is
often from abnormal bleeding, often in the gastrointestinal tract, such as from
The iron test checks
- Amount of iron bound to transferrin in the
- Amount of iron needed to bind to all of the
transferrin. This value is called the total iron-binding capacity
- Percentage of transferrin with iron bound to them. This
value is called transferrin saturation.
Why It Is Done
A test for iron is done to:
How To Prepare
Do not take iron supplements for 12
hours before having an iron test.
Iron levels change throughout
the day so it is best to do iron tests in the morning, when iron levels are
How It Is Done
The health professional drawing blood
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure to the site and then a