Iron Tests

Iron is needed to form normal red blood cells (RBC's). RBC's carry oxygen throughout the body. Iron is a critical part of hemoglobin, the protein in red blood cells that binds oxygen in the lungs and releases it as blood travels to other parts of the body. Iron is also needed by other cells, especially muscle (which contains another oxygen binding protein called myoglobin). Low iron levels can lead to anemia, in which the body does not have enough red blood cells. Other conditions can cause you to have too much iron in your blood.

SOME OF THE MOST COMMON TESTS FOR IRON IN THE BLOODSTREAM ARE:

  • Serum iron level - measures the level of iron in the liquid part of your blood.

  • Ferritin level - measures the amount of stored iron in your body. Ferritin is the main protein that stores iron for areas that need it, especially the liver and bone marrow. Bone marrow is the inside cavity in bones, where blood cells are made.

  • Total Iron Binding Capacity (TIBC) - measures the amount of transferrin, a blood protein that transports iron from the gut to the cells that use it. Your body makes transferrin in relationship to your need for iron; when iron stores are low, transferrin levels increase, while transferrin is low when there is too much iron. Usually about one third of the transferrin is being used to transport iron. Because of this, your blood serum has considerable extra iron-binding capacity, which is the Unsaturated Iron Biding Capacity (UIBC). The TIBC equals UIBC plus the serum iron measurement. Some laboratories measure UIBC, some measure TIBC, and some measure transferrin.

  • These tests are often ordered together, and the relative changes in each can help your doctor determine the cause of an abnormal result in one or more of these tests.

OTHER TESTS WHICH CAN BE USED TO HELP RECOGNIZE PROBLEMS WITH IRON IN THE BODY ARE:

  • Hemoglobin and Hematocrit - While not really tests of iron status alone, they are widely used parts of the Complete Blood Count (CBC) that can detect anemia; iron deficiency is a common cause of anemia. Another part of the CBC is the Mean (average) Cell Volume (MCV), which measures how big the red blood cells are. In iron deficiency (and in some other diseases as well), not enough hemoglobin is made, causing the red blood cells to be smaller than normal (microcytic) and paler than normal (hypochromic).

  • HFE gene test – The most common genetic disease in people whose ancestors came from northern Europe is hemochromatosis, a disease that causes your body to absorb too much iron. It is due to an inherited abnormality in a specific gene, called the HFE gene, that regulates the amount of iron absorbed from the gut. In people who have two copies of an abnormal form of the gene, the protein made by the gene cannot tell the cells in the gut when the body is "full" of iron, so the gut keeps on absorbing iron and excess iron damages many different organs. The HFE gene test uses a sample of blood drawn from you arm to see if you have the mutations that cause the disease (the most common is called C282Y).

  • Zinc Protoporphyrin is the part of hemoglobin that needs iron to help it carry oxygen. If there is not enough iron, another metal (such as zinc) will attach to the protoporphyrin instead. This test, which is simple to do using only a small amount of blood, is sometimes used as a screening test for iron deficiency, especially in children. Because lead prevents iron (but not zinc) from attaching to protoporphyrin, zinc protoporphyrin will also be high in severe cases of lead poisoning.

IRON TESTS ARE OFTEN USED TO EVALUATE THE FOLLOWING CONDITIONS:

Anemia

This term refers to the presence of too few red blood cells, which are needed to carry oxygen to the body. Many conditions can cause anemia, but iron deficiency is one of the most common. Normal iron levels are maintained by a balance between the amount of iron taken into the body and the amount of iron lost. Normally, we lose a small amount of iron each day, so if we take in too little iron, deficiency could develop. Unless a person follows a very poor diet, however, there is usually enough iron to prevent iron deficiency in healthy people. In certain situation, there is an increased need for iron. Persons with chronic bleeding from the gut (usually from ulcers or tumors), or women with heavy menstrual periods will lose more iron than normal and often develop iron deficiency. Women who are pregnant or breastfeeding lose iron to their baby, and can develop iron deficiency if not enough extra iron is taken. Children, especially during times of rapid growth, need extra iron and can develop iron deficiency.

Anemia can also occur in states where the body cannot use iron properly. In many chronic diseases, especially in cancers, autoimmune diseases, and with chronic infections (including AIDS), the body cannot properly use iron to make more red cells. As a result, production of transferrin decreases, serum iron is low (because little iron is being absorbed from the gut), and ferritin (the storage form of iron) increases.

Iron deficiency occurs in a range of severity. The mildest stage is iron depletion, which means the amount of functioning iron in your body is alright, but the body does not have any extra iron stores. Serum iron is usually normal in this stage. As iron deficiency worsens, called iron-deficient erythropoiesis (formation of red blood cells), all of your stored iron is gone and your body begins to produce more transferrin to increase iron transport. As this stage progresses, red cells are produced in normal numbers but they have less hemoglobin than normal (microcytic and hypochromic red cells). In iron-deficiency anemia, the most severe form of iron deficiency, the number of red cells produced is low, anemia develops, serum iron is low, ferritin is low, and transferrin and TIBC are high.

Excess Iron

Too much iron can lead to damage to a number of organs, including the heart, liver, pancreas (where insulin is made) and joints most commonly. The most common cause of iron excess is an inherited disease called hemochromatosis. In this disease, the body absorbs more iron than it needs from the gut, and the excess iron gradually accumulates, causing organ damage over many years. The disease is inherited when you get one copy of an abnormal form of the HFE gene from each of your parents (who show no evidence of the disease). Many people who have hemochromatosis will have no symptoms for their whole life, while others start to develop symptoms such as joint pain, abdominal pain, and weakness in their 20's or 30's. Heavy alcohol use seems to increase the amount of iron absorbed, while women are somewhat protected because they lose iron every month with their menstrual period. There is now a test to detect the abnormal form of the gene; this can be used if you have unexplained high iron levels or if you have a family history of hemochromatosis.

Iron poisoning occurs if a large amount of iron is taken all at once. While this is rare, it most commonly occurs in children who get hold of their mothers iron supplements or a bottle of vitamins with iron. If severe enough, iron poisoning can cause death, so it is a good idea to keep all iron supplements well out of the reach of children.

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.

MEANING OF TEST

Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.

OBTAINING THE TEST RESULTS

It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.