Iron

Serum iron and a total iron-binding capacity (TIBC), or sometimes a UIBC (unsaturated iron-binding capacity) or transferrin test, are ordered together, and a transferrin saturation calculated to determine how much iron is being carried in the blood. A ferritin test may also be ordered to evaluate a person's current iron stores.

These tests are used together to detect and help diagnose iron deficiency or iron overload. In people with anemia, these tests can help determine whether the condition is due to iron deficiency or another cause, such as chronic illness. Iron tests are also ordered if a doctor suspects that a person has iron poisoning and to screen for hereditary hemochromatosis, an inherited condition associated with excessive iron storage.

Serum iron tests are not ordered routinely. They are typically ordered as follow-up tests when abnormal results are found on routine tests such as a CBC, hemoglobin, and hematocrit. They may also be ordered when iron deficiency or iron overload is suspected.

Early iron deficiency usually causes no concerns at all. If a person is otherwise healthy, symptoms seldom appear before the hemoglobin in the blood drops below a certain level (about 10 g per deciliter). As iron stores continue to be depleted, signs that your body is low in iron may develop. As your condition progresses and anemia begins to develop, some of the signs and symptoms that appear may include:

• Chronic fatigue/tiredness
• Dizziness
• Weakness
• Headaches

If the iron-deficiency anemia is severe, shortness of breath, dizziness, 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 pica (cravings for specific substances, such as 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 finger- and toe-nails.

A serum iron and other iron tests may be ordered when iron overload (hemochromatosis) is suspected. Symptoms of high iron levels will vary from person to person and tend to worsen over time. They are associated with iron accumulation and can be similar to those seen with other conditions. Symptoms may include:

• Joint pain
• Fatigue, weakness
• Lack of energy
• Abdominal pain
• Loss of sex drive
• Heart problems

When a child is suspected to have ingested iron tablets, a serum iron test is ordered to detect and help assess the severity of the poisoning. Iron tests may also be ordered periodically when iron deficiency or overload is being treated to evaluate the effectiveness of treatment.

Serum iron levels are often evaluated in conjunction with other iron tests. A summary of the changes in iron tests seen in various diseases of iron status is shown in the table below.

A low iron with a high transferrin or TIBC is usually due to iron deficiency. In chronic diseases, both iron and transferrin or TIBC are typically low. Iron deficiency is usually due to long-term or heavy bleeding. However, it can also be due to increased iron requirements (in pregnancy), rapid growth (in children), poor diet, and problems with absorption (stomach or intestinal disease).

High levels of serum iron can occur as the result of multiple blood transfusions, iron injections into muscle, lead poisoning, liver disease, or kidney disease. It can also be due to the genetic disease, hemochromatosis.

Recent consumption of iron-rich foods, or of iron pills or tablets, can affect test results, as can recent blood transfusions. Alcohol and drugs, such as oral contraceptives and methotrexate, can increase iron test levels, while testosterone, large doses of aspirin, metformin, and ACTH (adrenocorticotropic hormone) can decrease them.

Stress and sleep deprivation can temporarily decrease serum iron levels.