Total iron-binding capacity

Total iron-binding capacity (TIBC) 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.

The TIBC should not be confused with the UIBC, or "unsaturated iron binding capacity" ( and ). 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.

Usual values


Normal reference ranges are:
 * Serum iron: Male 65–177 μg/dL (11.6–31.7 μmol/L); Female 50–170 μg/dL (9.0–30.4 μmol/L)
 * TIBC: 250–370 μg/dL (45-66 μmol/L)
 * Transferrin saturation: Male 20–50%; Female 15–50%
 * Serum ferritin: Male 20-250 μg/L, Female 15-150 μg/L

μg/dL = micrograms per deciliter; μmol/L = micromoles per litre.

Laboratories often use different units and "normal" may vary by population and the lab techniques used. Look at the individual laboratory reference values to interpret a specific test (for instance, your own).