TIBC / Transferrin Saturation / UIBC
Definition
Iron is carried in the blood bound to a protein called transferrin. These tests measure transferrin's iron-carrying capacity:
| Test | What it measures |
|---|---|
| TIBC | The blood's total capacity to bind iron via transferrin |
| UIBC | The unused capacity of transferrin to bind iron |
| Transferrin Saturation | What percentage of transferrin is filled with iron |
Mathematical relationship: TIBC = Serum Iron + UIBC
Purpose
To distinguish iron deficiency from other types of anemia; to detect iron overload.
Results
- High TIBC, insufficient iron stores in the body. May suggest iron deficiency anemia or late pregnancy
- Low TIBC, hemolytic anemia, low blood protein, inflammatory conditions, liver disease (cirrhosis), malnutrition, pernicious anemia, or sickle cell anemia
Normal Values
| Parameter | Male | Female |
|---|---|---|
| TIBC | 171 to 505 mcg/dL (30.6 to 90.3 µmol/L) | 149 to 492 mcg/dL (26.7 to 88.0 µmol/L) |
| Iron saturation | 20% to 50% | 15% to 45% |
Normal reference ranges may vary slightly between laboratories.
Serum iron normal range:
| Male | Female | |
|---|---|---|
| Serum iron | 59 to 158 mcg/dL (10.6 to 28.3 µmol/L) | 37 to 145 mcg/dL (6.6 to 25.9 µmol/L) |
Risks and Limitations
Fasting for 8 hours is required before the test.
How UIBC relates to TIBC: UIBC is a routinely measured standard parameter in clinical chemistry; serum iron, UIBC, and TIBC are evaluated together, while transferrin saturation is calculated from them. The relationship is definitional: `TIBC = Serum Iron + UIBC`.
Some laboratories measure TIBC directly, others measure UIBC and calculate TIBC. This difference does not change how your report is interpreted.