Also Known As
Total iron-binding capacity
Total iron saturation
Transferrin saturation
Unsaturated iron-binding capacity
Formal Name
Total Iron Binding Capacity; Unsaturated Iron Binding Capacity; Transferrin; Transferrin Saturation
This article was last reviewed on
This article waslast modified on 9 May 2022.
At a Glance
Why Get Tested?

To learn about your body's iron stores

When To Get Tested?

When your doctor suspects you may have too much or too little iron in your body because of a variety of conditions

Sample Required?

A blood sample taken from a vein in your arm

Test Preparation Needed?

You may be instructed to fast for 12 hours before the test; in this case, only water is allowed.

On average it takes 7 working days for the blood test results to come back from the hospital, depending on the exact tests requested. Some specialist test results may take longer, if samples have to be sent to a reference (specialist) laboratory. The X-ray & scan results may take longer. If you are registered to use the online services of your local practice, you may be able to access your results online. Your GP practice will be able to provide specific details.

If the doctor wants to see you about the result(s), you will be offered an appointment. If you are concerned about your test results, you will need to arrange an appointment with your doctor so that all relevant information including age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), can be considered.

Lab Tests Online-UK is an educational website designed to provide patients and carers with information on laboratory tests used in medical care. We are not a laboratory and are unable to comment on an individual's health and treatment.

Reference ranges are dependent on many factors, including patient age, sex, sample population, and test method, and numeric test results can have different meanings in different laboratories.

For these reasons, you will not find reference ranges for the majority of tests described on this web site. The lab report containing your test results should include the relevant reference range for your test(s). Please consult your doctor or the laboratory that performed the test(s) to obtain the reference range if you do not have the lab report.

For more information on reference ranges, please read Reference Ranges and What They Mean.

What is being tested?

Total Iron Binding Capacity, or TIBC, measures the total capacity of your blood to bind and transport iron, and therefore reflects your body's iron stores. TIBC correlates with the amount of the protein transferrin in your blood, available to bind iron. Transferrin is a protein that attaches iron molecules and transports iron in the blood plasma. Transferrin is largely made in the liver and regulates your body’s iron absorption into the blood. While the two tests (TIBC and transferrin) are different, they measure essentially the same thing and most laboratories only measure one or the other. A few laboratories are now measuring the number of sites on transferrin that are not already carrying iron; this is referred to as unsaturated iron binding capacity (UIBC). This number can be added to the serum iron to calculate the TIBC.

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Common Questions
  • How is it used?

    TIBC or transferrin are typically used along with iron and ferritin to evaluate people suspected of having too much or too little iron stored within their body. Usually, about one third of the transferrin measured is being used to transport iron, and this is called transferrin saturation. In iron deficiency, iron is low and fewer transferrin binding sites are used. This results in a low transferrin saturation, but an increased TIBC. In iron overload, such as in haemochromatosis, iron and transferrin saturation will be high and TIBC will be low or normal.
    Because transferrin is made in the liver, TIBC and transferrin will also be low with liver disease.

  • When is it requested?

    TIBC (or transferrin) measurements may be requested when it appears that you have too much or too little iron in your system. If you have anaemia, especially if the red cells are small and pale (microcytic and hypochromic), this may be due to iron deficiency and iron tests are usually performed. If your doctor suspects you may have too much iron, or if you have a family history of haemochromatosis, iron and TIBC (or transferrin or UIBC) may be used to see if further testing is needed.

  • What does the test result mean?

    High TIBC or transferrin, or low transferrin saturation, usually indicates iron deficiency. A low TIBC or transferrin, or high transferrin saturation may occur if you have haemochromatosis (too much stored iron). Other causes of abnormal results include anaemia caused by infections and chronic diseases, malnutrition, cirrhosis, or nephrotic syndrome (a kidney disease that causes loss of protein in urine).

    A summary of the changes in iron tests seen in various diseases of iron status is shown in the table below.

    Disease Iron TIBC/Transferrin UIBC % Transferrin Saturation Ferritin
    Iron Deficiency Low High High Low Low
    Haemochromatosis High Low Low High High
    Chronic Illness Low Low Low/Normal Low Normal/High
    Iron Poisoning High Normal Low High Normal
  • Is there anything else I should know?

    Taking the oral contraceptive pill can result in a higher TIBC result.

    Taking chloramphenicol can decrease TIBC levels. Some laboratories routinely only use studies of the red cells (FBC) and ferritin to investigate anaemia and monitor treatment.

  • Does transferrin actually move iron around my body?

    Yes. Transferrin attaches to iron and then transports and releases it in your bloodstream.