MedlinePlus 003489 | ||
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LOINC 14800-7, 35215-3, 2501-5 | ||
Total iron-binding capacity (TIBC) or sometimes transferrin iron-binding capacity is a medical laboratory test that measures the blood's capacity to bind iron with transferrin. It is performed by drawing blood and measuring the maximum amount of iron that it can carry, which indirectly measures transferrin since transferrin is the most dynamic carrier. TIBC is less expensive than a direct measurement of transferrin.
Contents
The TIBC should not be confused with the UIBC, or "unsaturated iron binding capacity" (22753-8 and 35216-1). The UIBC is calculated by subtracting the serum iron from the TIBC.
Interpretation
Taken together with serum iron and percent transferrin saturation clinicians usually perform this test when they are concerned about anemia, iron deficiency or iron deficiency anemia. However, because the liver produces transferrin, alterations in function (such as cirrhosis, hepatitis, or liver failure) must be considered when performing this test. It can also be an indirect test of liver function, but is rarely used for this purpose.
The percent transferrin saturation (i.e., the result of the formula of serum iron/TIBC x 100) can also be a useful indicator.
These examples demonstrate that to properly understand a value for TIBC, one also must know the serum iron, the percent transferrin saturation, and the individual clinical situation. In modern laboratory testings, serum ferritin levels are generally accepted as reliable single indicators of the presence of iron deficiency.
Usual values
Laboratories often use different units of measurement and "normal" may vary by population and the laboratory techniques used. Look at the individual laboratory reference values to interpret a specific test (for instance, your own). Example reference ranges are:
μg/dL = micrograms per deciliter; μmol/L = micromoles per litre.