This article was last reviewed on
This article waslast modified on September 23, 2019.
Why Get Tested?
To evaluate your body's current level of iron; to help diagnose iron deficiency or iron overload
When To Get Tested?
When you have low hemoglobin and hematocrit on a complete blood count (CBC); when your healthcare practitioner suspects that you may have too little iron (deficiency) or too much iron (overload) in your body
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
You may be instructed to have your blood drawn in the morning and/or fast for 12 hours before the test; in this case, only water is allowed. Follow any instructions from your healthcare practitioner and/or from the laboratory performing the test.
What is being tested?
Common Questions
- How is it used?
Iron tests are used to assess the amount of iron circulating in the blood, the total capacity of the blood to transport iron, and the amount of stored iron in the body. Testing may also help differentiate various causes of anemia.Iron tests are often ordered together, and the results of each can help identify iron deficiency, iron deficiency anemia, or too much iron in the body (overload).
When is it ordered?
Iron tests may be ordered when results from a routine complete blood count (CBC) show that a person's hemoglobin and hematocrit are low and their red blood cells are smaller and paler than normal (microcytic and hypochromic), suggesting iron deficiency anemia even though other clinical symptoms may not have developed yet.
- Chronic fatigue/tiredness
- Dizziness
- Weakness
- Headaches
- Pale skin (pallor)
Iron tests may be ordered when iron overload is suspected. Signs and symptoms of iron overload will vary from person to person and tend to worsen over time. They are due to iron accumulation in the blood and tissues. These may include:
- Joint pain
- Fatigue, weakness
- Lack of energy
- Abdominal pain
- Loss of sex drive
- Organ damage, such as in the heart and/or liver
When a child is suspected to have ingested an excessive amount of iron tablets, a serum iron test is ordered to detect and help assess the severity of the poisoning.
What does the test result mean?
A summary of the changes in iron tests seen in various diseases of iron status is shown in the table below.
Disease | Iron | TIBC/Trans ferrin | UIBC | % Transferrin Saturation | Ferritin |
Iron Deficiency | Low | High | High | Low | Low |
Hemochroma tosis/ Hemosiderosis | High | Low | Low | High | High |
Chronic Illness | Low | Low/Normal | Low/ Normal | Low/Normal | Normal/ High |
Hemolytic Anemia | High | Normal/Low | Low/ Normal | High | High |
Sideroblastic Anemia | Normal/ High | Normal/Low | Low/ Normal | High | High |
Iron Poisoning | High | Normal | Low | High | Normal |
Iron deficiency
The early stage of iron deficiency is the slow depletion of iron stores. This means there is still enough iron to make red cells, but the stores are being used up without adequate replacement. The serum iron level may be normal in this stage, but the ferritin level will be low.
As iron deficiency continues, all the stored iron is used and the body tries to compensate by producing more transferrin to increase iron transport. The serum iron level continues to decrease and transferrin and TIBC and UIBC increase. As this stage progresses, fewer and smaller red blood cells are produced, eventually resulting in iron deficiency anemia.
Iron overload
If the iron level is high, the TIBC, UIBC and ferritin are normal and the person has a clinical history consistent with iron overdose, then it is likely that the person has iron poisoning. Iron poisoning occurs when a large dose of iron is taken all at once or over a short period of time. Iron poisoning in children is almost always acute, occurring in children who ingest their parents' iron supplements. In some cases, acute iron poisoning can be fatal.
A person who has mutations in the HFE gene is diagnosed with hereditary hemochromatosis. However, while many people who have hemochromatosis will have no symptoms for their entire life, others will start to develop symptoms such as joint pain, abdominal pain, and weakness in their 30's or 40's. Men are affected more often than women because women lose blood during their reproductive years through menstruation.
Iron overload may also occur in people who have hemosiderosis and in those who have had repeated transfusions. This may occur with sickle cell anemia, thalassemia major, or other forms of anemia. The iron from each transfused unit of blood stays in the body, eventually causing a large buildup in the tissues. Some people with alcoholism and with chronic liver disease also develop iron overload.
Is there anything else I should know?
Recent consumption of iron-rich foods or iron supplements can affect test results, as can recent blood transfusions.
Normal iron levels are maintained by a balance between the amount of iron taken into the body and the amount of iron lost. Normally, a small amount of iron is lost each day, so if too little iron is taken in, a deficiency will eventually develop. Unless a person has a poor diet, there is usually enough iron to prevent iron deficiency and/or iron deficiency anemia in healthy people.
In certain situations, there is an increased need for iron. Persons with chronic bleeding from the digestive tract (usually from ulcers or tumors such as colorectal cancer) or women with heavy menstrual periods will lose more iron than normal and can 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 in. Children, especially during times of rapid growth, may need extra iron and can develop iron deficiency. Iron deficiency can also be seen in malabsorption diseases such as celiac disease.
Low serum iron can also occur in states where the body cannot mobilize and use storage iron properly. In many chronic inflammatory conditions, especially in cancers, autoimmune diseases, and with chronic inflammations or chronic infections (including AIDS), the body cannot properly use iron to make more red cells. Under these conditions, production of transferrin decreases, and serum iron is low because little iron is being absorbed from the gut and storage iron can't get mobilized, and ferritin increases.
Do all people with iron deficiency have anemia? What are the symptoms?
Iron deficiency refers to a decrease in the amount of iron stored in the body, while iron deficiency anemia refers to a drop in the number of red blood cells (RBCs), hemoglobin and hematocrit caused by not having enough stored iron (there are many other causes of anemia). It typically takes several weeks after iron stores are depleted for the level of hemoglobin and production of RBCs to be affected and for anemia to develop. There usually are few symptoms early in iron deficiency, but as the condition worsens and blood levels of hemoglobin and RBCs decrease, then ongoing weakness and fatigue can eventually develop.
As your iron continues to be depleted, you may have shortness of breath and dizziness. If the anemia is severe, chest pain, headaches, and leg pains may occur. Children may develop learning (cognitive) disabilities. Besides the general symptoms of anemia, there are certain symptoms that are characteristic of iron deficiency. These include dysphagia, pica (cravings for specific substances, such as ice, corn starch, licorice, chalk, dirt, or clay), a burning sensation in the tongue or a smooth tongue, sores at the corners of the mouth, and spoon-shaped fingernails and toenails.
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