Situations Where Iron Tests Are Used Anemia
Anemia occurs when the amount of hemoglobin (found in the red blood cells) drops below normal. 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 will eventually develop. Unless a person has a poor diet, however, there is usually enough iron to prevent iron deficiency in healthy people. In certain situations, 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 develop iron deficiency. Women who are pregnant or breast feeding 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 may be normal in this stage, but ferritin will be low. As iron deficiency worsens, all of your stored iron is gone and your body begins to produce more transferrin to increase iron transport. Serum iron becomes low, and transferrin and TIBC are high. As this stage progresses, fewer red cells are produced. In iron-deficiency anemia, the number of red cells is decreased, and many of the cells appear smaller and paler than normal.
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. 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, usually when you get one copy of an abnormal HFE gene from each of your parents. People with only one abnormal HFE gene 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.
Some people develop iron overload but do not have the genetic disease hemochromatosis. Their condition is referred to as secondary iron overload or hemosiderosis. This may occur in patients who have multiple transfusions, such as those with thalassemia or other forms of anemia. The iron from each transfused unit of blood stays in the body, eventually causing a large build-up in the tissues. Some alcoholics with chronic liver disease also develop hemosiderosis.
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. 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.
A summary of the changes in iron tests seen in various diseases of iron status is shown in the table.
|
Disease |
Iron |
TIBC |
UIBC |
Ferritin |
|
Iron deficiency |
Low |
High |
High |
Low |
| Chronic Illness |
Low |
Low |
Low-normal |
Normal-high |
|
Hemochromatosis |
High |
Low |
Low |
High |
|
Iron Poisoning |
High |
Normal |
Low |
Normal |
