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A total iron binding capacity (TIBC) test is a type of blood test that gauges whether there’s too much or too little iron in your bloodstream.
Iron is a type of mineral found in all of the body’s cells. You get the iron you need through your diet. Once iron enters the body, it’s carried throughout your bloodstream by a protein called transferrin, which is produced by your liver. The TIBC test evaluates how well transferrin carries iron through your blood.
In your blood, iron helps form hemoglobin. Hemoglobin is an important protein in red blood cells that helps carry oxygen throughout the body so it can function normally. Iron is considered an essential mineral because hemoglobin can’t be made without it.
Iron can be found in numerous different foods, including:
The Food and Nutrition Board at the Institute of Medicine recommends people consume certain amounts of iron each day. For healthy people, it recommends the following amounts:
The Centers for Disease Control and Prevention recommends that pregnant females of all ages take 30 mg/day. Pregnant and lactating women may need different amounts of iron than those recommended. Check with your doctor to find out how much you need.
Doctors typically order TIBC tests to check for medical conditions that cause abnormal iron levels.
Your doctor may perform a TIBC test if you’re experiencing the symptoms of anemia, or a lack of iron in the blood. In the United States, iron is the most common type of dietary deficiency. Iron deficiency is usually the cause of anemia, but the condition may also be triggered by increased blood loss during menstruation, pregnancy, and chronic infections.
The symptoms of low iron levels include:
A TIBC test may also be ordered if your doctor suspects you have too much iron in your blood. High levels of iron most commonly indicate an underlying medical condition. Some common causes of high iron levels include:
In rare cases, high iron levels may be caused by an overdose of vitamins or iron supplements.
The symptoms of high iron levels include:
Call your doctor if you’re experiencing the symptoms of low or high iron levels. If any underlying conditions are left untreated, you’re at an increased for serious complications, such as:
Fasting is required for a TIBC test to ensure the most accurate results. This means you shouldn’t eat or drink anything for at least eight hours before the test.
Some medications can also affect the results of a TIBC test, so it’s important to tell your doctor about any prescription or over-the-counter medications you’re taking. Your doctor may tell you to stop taking certain medications before the test. However, you shouldn’t stop taking any medications without talking to your doctor first.
Some medications that can affect the test results include:
A TIBC test may be ordered along with a serum iron test, which measures the amount of iron in your blood. Together, these tests can help determine whether there’s an abnormal amount of iron in your blood.
The tests involve taking a small sample of blood. Blood is usually drawn from a vein or artery in the hand or the bend of the elbow. The following steps will occur:
Blood tests carry few risks. Some people have a slight bruise or experience soreness around the area where the needle was inserted. However, this usually goes away within a few days.
Complications from blood tests are rare, but they can occur. Such complications include:
Normal values for the TIBC test can vary among laboratories. However, most laboratories define a normal range as 240 to 450 micrograms per deciliter (mcg/dL).
A total iron binding capacity value above 450 mcg/dL usually means that there’s a low level of iron in your blood. This may be caused by a lack of iron in the diet, increased blood loss during menstruation, pregnancy, or a chronic infection.
A total iron binding capacity value below 240 mcg/dL usually means that there’s a high level of iron in your blood. This may be caused by:
Your doctor will explain what your individual results mean for you and what the next steps should be.
Written by: Erica Cirino
Medically reviewed on: Feb 23, 2016: Steve Kim, MD
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