Total iron-binding capacity | |
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Synonyms | Transferrin iron-binding capacity |
MedlinePlus | 003489 |
LOINC | 2500-7, 14800-7, 35215-3 |
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.[1] Transferrin can bind two atoms of ferric iron (Fe3+) with high affinity. It means that transferrin has the capacity to transport approximately from 1.40 to 1.49 mg of iron per gram of transferrin present in the blood.[2]
It is performed by drawing blood and measuring the maximum amount of iron that it can carry, which indirectly measures transferrin[3] since transferrin is the most dynamic carrier. If TIBC values are known, the transferrin concentration can be estimated with the following formulas:[2]
To measure TIBC in the blood is less expensive than a direct measurement of transferrin.[4][5]
The TIBC should not be confused with the unsaturated iron-binding capacity or UIBC (LOINC 2501-5, 22753-8 & 35216-1). The UIBC is calculated by subtracting the serum iron from the TIBC.[6]