Iron Saturation (TSAT): Normal Range & What High or Low Means
Also known as: Transferrin saturation, TSAT, iron sat, transferrin sat
Iron saturation — also called transferrin saturation or TSAT — is the percentage of your iron-transport protein (transferrin) that is actually carrying iron. It's calculated from serum iron and total iron-binding capacity and is a sensitive early marker of iron status. A normal iron saturation is roughly 20–50%; a low value suggests iron deficiency, while a high value can signal iron overload such as hemochromatosis.
Iron Saturation normal range
| Category | Range (%) |
|---|---|
| Normal | 20–50%Some labs cite 15–45% |
| Low | < 20%Suggests iron deficiency |
| High | > 45–50%Suggests iron overload |
| Overload concern | > 45% (women) / > 50% (men)Prompts evaluation for hemochromatosis |
| Reference ranges vary by lab | Use your own reportCutoffs differ between laboratories |
Reference ranges vary by laboratory. Use the range printed on your own report as the definitive comparison.
What high Iron Saturation can mean
- Hereditary hemochromatosis or other iron overload
- Frequent blood transfusions or iron supplementation/infusions
- Liver disease
- Hemolytic anemia (excess iron release from red cells)
What low Iron Saturation can mean
- Iron deficiency (the most common cause of a low saturation)
- Chronic inflammation or infection (anemia of chronic disease)
- Blood loss, including heavy menstrual periods
- Poor dietary iron intake or absorption
What to do about an abnormal result
- Compare your value to the range on your own report — lab cutoffs differ.
- Iron saturation is interpreted with ferritin, serum iron, and TIBC, not on its own.
- A persistently high saturation with high ferritin prompts evaluation for hemochromatosis, sometimes including genetic testing.
- Don't self-diagnose from one number — a low saturation is confirmed and its cause investigated before treatment.
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Frequently asked questions
What is a normal transferrin saturation?
A normal transferrin (iron) saturation is roughly 20–50%, though some labs use slightly different cutoffs. Below about 20% suggests iron deficiency, while consistently above 45–50% raises concern for iron overload.
What does high iron saturation mean?
A high iron saturation means a large share of your transferrin is loaded with iron, which can indicate iron overload conditions like hereditary hemochromatosis, repeated transfusions, or liver disease. When it's high along with high ferritin, doctors often investigate for hemochromatosis.
Can iron saturation be low with normal ferritin?
Yes. Early iron deficiency and anemia of chronic disease can lower saturation while ferritin is still normal or even elevated, because ferritin also rises with inflammation. That's why doctors look at the full iron panel together.
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Medically reviewed by Antonieta Rueda, MD and Kyle R. Toth, MD · Last reviewed July 6, 2026
This article is for informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or your lab results.