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Iron is found in all of the body’s cells. A total iron binding capacity (TIBC) test is a type of blood test that gauges whether there’s too much or too little of the mineral in your bloodstream.
You get the iron you need through your diet. Iron is present in numerous foods, including:
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.
Once it’s in your blood, iron helps form hemoglobin. Hemoglobin is an important protein in red blood cells (RBCs) 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.
The National Institutes of Health (NIH) recommend that healthy people get the following amounts of iron through their diet:
Infants and children
- 6 months old or younger: 0.27 milligrams per day (mg/day)
- 7 months old to 1 year old: 11 mg/day
- ages 1 to 3 years old: 7 mg/day
- ages 4 to 8 years old: 10 mg/day
- ages 9 to 12 years old: 8 mg/day
Males (teens and adults)
- age 13 years old: 8 mg/day
- ages 14 to 18 years old: 11 mg/day
- ages 19 years old or older : 8 mg/day
Females (teens and adults)
- age 13 years old: 8 mg/day
- ages 14 to 18 years old: 15 mg/day
- ages 19 to 50 years old: 18 mg/day
- ages 51 years old or older: 8 mg/day
- during pregnancy: 27 mg/day
- ages 14 to 18 years old, if lactating: 10 mg/day
- ages 19 to 50 years old, if lactating: 9 mg/day
Certain people, such as those diagnosed with an iron deficiency, may require different amounts of iron than those recommended above. Check with your doctor to find out how much you need each day.
Doctors typically order TIBC tests to check for medical conditions that cause abnormal iron levels.
Causes of low iron levels
The symptoms of low iron levels include:
- feeling tired and weak
- an increase in infections
- always feeling cold
- a swollen tongue
- difficulty concentrating at school or work
- delayed mental development in children
Causes of high iron levels
A TIBC test may 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. In rare cases, high iron levels may be caused by an overdose of vitamins or iron supplements.
The symptoms of high iron levels include:
Fasting is required to ensure the most accurate results. This means you shouldn’t eat or drink anything for at least 8 hours before the TIBC 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 your healthcare provider 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 in the hand or the bend of the elbow. The following steps will occur:
- A healthcare provider will first clean the area with an antiseptic and then tie an elastic band around your arm. This will make your veins swell with blood.
- Once they find a vein, they’ll insert the needle. You can expect to feel a slight prick or stinging sensation when the needle goes in. However, the test itself isn’t painful.
- They’ll only collect enough blood required to perform the test and any other blood tests your doctor may have ordered.
- After enough blood has been drawn, they’ll remove the needle and place a bandage over the puncture site. They’ll tell you to apply pressure to the area with your hand for a few minutes.
- The blood sample will then be sent to a laboratory for analysis.
- Your doctor will follow up with you to discuss the results.
The TIBC test can also be performed with an at-home test kit from the company LetsGetChecked. This kit uses blood from the fingertip. If you choose this home test, you’ll also need to send your blood sample off to a laboratory. Your test results should be available online within 5 business days.
Companies such as Life Extension and Pixel by LabCorp also have test kits that can be purchased online, and your doctor doesn’t have to order the laboratory test for you. However, you’ll still have to visit a laboratory in person to provide your blood sample.
Blood tests pose 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 for adults as 250 to 450 micrograms per deciliter (mcg/dL).
A TIBC 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
A TIBC value below 250 mcg/dL usually means that there’s a high level of iron in your blood. This may be caused by:
- hemolytic anemia, a condition that causes RBCs to die prematurely
- sickle cell anemia, an inherited condition that causes RBCs to change shape
- hemochromatosis, a genetic condition that causes a buildup of iron in the body
- iron or lead poisoning
- frequent blood transfusions
- liver damage
Your doctor will explain what your individual results mean for your health and what the next steps should be.
If it turns out that you have an underlying condition, it’s important for you to seek treatment. If any underlying conditions are left untreated, you’re at an increased for serious complications, such as: