Biomarker · Iron
Transferrin saturation and TIBC
Transferrin saturation shows how much of the body's iron-transport protein is loaded with iron. How it is used with ferritin to detect iron deficiency and iron overload.
Written by LON6EVITY Editorial Team · Last updated
What it measures
Iron travels in the blood bound to a protein called transferrin. Iron tests measure serum iron, total iron-binding capacity (TIBC) and transferrin saturation — the percentage of transferrin carrying iron. MedlinePlus lists these alongside ferritin as the usual iron tests.
How it is used
Low saturation with low ferritin points toward iron deficiency. High saturation, especially with high ferritin, can suggest iron overload such as hemochromatosis and usually leads to further testing.
Things that affect it
Serum iron changes during the day and after meals or supplements, so tests are often done in the morning after fasting. Inflammation can alter these results.
Reference ranges
Reference ranges differ between laboratories, units and methods, and depend on age, sex and your overall clinical picture. A single result is not a diagnosis — interpret it with a qualified clinician.
Factors that can affect the result
- Recent meals and supplements
- Time of day
- Inflammation
- Pregnancy
- Oral contraceptives
Questions people commonly ask
- Why is ferritin not enough on its own?
- Ferritin also rises with inflammation, so saturation helps interpret it.
Related biomarkers
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Understand your biomarkers in context
What does this mean for your own health data? Log your results, follow trends over time and bring an organised summary to your next doctor's appointment.
Sources
- Iron Tests. MedlinePlus, U.S. National Library of Medicine.