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Iron Saturation (Transferrin Saturation)

Normal range: 20 – 50 % (higher is better)

Iron saturation (also called transferrin saturation) tells you what percentage of your iron-carrying protein is actually loaded with iron. It is calculated as serum iron divided by TIBC. Low saturation means your iron transport is running mostly empty (iron deficiency). High saturation (above 50%) means it is running at full capacity, which may suggest iron overload or hereditary hemochromatosis.

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What can cause low Iron Sat.?

A normal Iron Sat. is 20 – 50 %. Higher is better.

Low iron saturation is the hallmark of iron deficiency. There is too little iron relative to the available transferrin carriers. Blood loss, poor dietary intake, and impaired absorption are the most common causes.

High iron saturation (above 45-50%) raises suspicion for hereditary hemochromatosis, a genetic disorder affecting about 1 in 200 people of Northern European descent. Excessive supplementation and repeated transfusions can also cause high saturation.

The same lifestyle changes that improve serum iron and TIBC apply here. If saturation is low, increasing dietary iron and treating any underlying blood loss are the priorities. If saturation is persistently high, genetic testing for hemochromatosis may be warranted. Therapeutic phlebotomy (regular blood donation) is the standard treatment for iron overload.

Iron saturation (transferrin saturation) tells you what percentage of your iron-carrying protein is actually loaded with iron. Low saturation means iron deficiency. High saturation (above 45-50%) raises suspicion for hereditary hemochromatosis, a genetic disorder affecting about 1 in 200 people of Northern European descent.

How does Iron Saturation change with age?

Iron Saturation stays relatively flat across adult ages (correlation with age, r = -0.03). Most of the spread in the chart below comes from differences between people rather than from age.

Iron Saturation is stable with age, chart with median and linear trend

Biomarkers related to Iron Sat.

Iron Sat. is most highly correlated with Hematocrit and Mean Platelet Volume. Here are the top biomarkers correlated with Iron Sat., based on 500,000 tests done by Empirical Health.

1 Hematocrit
+31%
2 MPV
+26%
3 Iron
+8%
4 Ferritin
+7%
5 Sodium
+6%
6 ALT
+5%
7 Chloride
+4%
8 hs-CRP
−3%
9 MCH
+3%
10 LDL
+3%

The percentage shows how strongly two biomarkers move together. A higher number means the relationship is stronger. Green = rises and falls together. Orange = one rises as the other falls.

Frequently asked questions about Iron Sat.

Iron Sat. test cost

Iron Sat. isn't ordered on its own — it's derived from an iron panel, which runs about $30–$65 at Quest or LabCorp, or $190 as part of a 100+ biomarker panel from Empirical Health.

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Where to test Iron Sat.

You can measure your Iron Sat. for at 2,200+ testing locations across the US. Click below and enter your zip code to browse locations near you.

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