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Transferrin saturation (TSAT)
The percentage of transferrin's iron seats actually occupied: serum iron / TIBC × 100%. A key iron-metabolism figure.
Other names: Transferrin saturation, TSAT, iron saturationSection: Iron status
Updated: August 31, 2026·MedProtect editorial team Reference information — not a diagnosis or a prescription
In shortTSAT shows what share of iron-transport capacity is occupied. A typical guide is 20–50%. Low saturation points to iron deficiency — including the latent stage before anemia — while sustained high saturation suggests iron overload (hemochromatosis).
Reference ranges
Group
Reference range
Adults — typical range (international reference, not a national standard)
about 20–50%; the report's reference applies
The 20–50% guide appears in international references (not a national standard). Thresholds for diagnosing deficiency and overload are set by the provider from the full iron panel. Reference ranges vary between laboratories and assays — use the range printed on your own lab report.
Check your value
Enter your result — we will show how it compares with a typical range. Match the units of the selected row.
Approximate comparison with a typical range, not a diagnosis. Reference intervals vary by laboratory and method — check your report; result interpretation is done by a doctor.
What this marker is
TSAT = serum iron / TIBC × 100%. Because it is a ratio, it captures both sides of iron metabolism at once: how much iron circulates and how much transport capacity stands empty.
The test is drawn in the morning fasting, because serum iron has daily fluctuations that shift the calculation.
When it is high
HemochromatosisInherited iron overload: saturation persistently above 45–50% prompts genetic evaluation.
Repeated transfusionsFrequent blood transfusions overload the body with iron.
When it is low
Iron deficiencySaturation below 15–20% is typical of iron deficiency, including the latent stage.
Anemia of chronic diseaseInflammation lowers saturation moderately despite normal stores.
What can skew the result
These factors can shift the value without any disease — worth considering before a retest:
Time of day (morning peak)Iron supplements beforehandInflammation
How to prepare
Morning fasting; calculated automatically from the serum iron + TIBC pair.
When a retest makes sense
An abnormal result is rechecked fasting in the morning after 4–6 weeks, together with ferritin.
Who usually reviews this result
A result outside the reference range is usually reviewed by: your GP or primary care doctor; a hematologist or gastroenterologist as appropriate. Bring your lab report and any previous results to the appointment.
Names used on lab reports
Your report may use any of these names: TSATTransferrin saturationIron saturation
Units
Measured in: %
Several markers on your report?
See how MedProtect explains results in the app: the whole report, a check of the recognized values, and a clear breakdown.
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