Nutrients
Transferrin saturation (TSAT)
Iron saturation, TSAT
Included in Baseline and Complete.
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Transferrin saturation is calculated from your serum iron and TIBC results. It shows what share of your blood's iron-carrying capacity is in use, which helps assess both low iron and iron overload.
An early clue about iron overload.
Low saturation, together with low ferritin, supports iron deficiency. High saturation is often the earliest blood sign of hereditary hemochromatosis, an inherited condition in which the body absorbs too much iron, and European liver guidelines use it with ferritin to decide who needs further testing.
Saturation varies quite a bit from day to day, so morning samples are preferred and an unexpected result is often rechecked before drawing conclusions.
Ferritin shows stored iron. Saturation shows iron in transit.
Questions
Does a high result mean I have hemochromatosis?
A single result can't tell you that. Saturation can also be high with liver conditions, recent iron intake, or normal day-to-day variation. If it stays high on repeat testing, a clinician may suggest further tests, which can include genetic testing.
How is this different from ferritin?
Ferritin reflects the iron your body has stored, while saturation reflects the iron moving in your blood right now. Ferritin also rises with inflammation, so saturation helps show whether a high ferritin is really about iron.