Transferrin Saturation
Calculates transferrin saturation from serum iron and total iron binding capacity.
When to use
Assessment of iron deficiency or overload in adults, with ferritin and blood count.
Pearls and pitfalls
- Saturation is the ratio of serum iron to total iron binding capacity, as a percentage.
- Inflammation lowers binding capacity and can raise saturation without true overload.
- Ferritin is an acute phase reactant and can be normal in iron deficiency with inflammation.
- No single index confirms hemochromatosis; confirm with genetics and magnetic resonance when indicated.
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Formula
TSAT (%) = serum iron (µg/dL) / total iron binding capacity (µg/dL) × 100.
Evidence
Laboratory index used to estimate iron availability for erythropoiesis and recognize overload.
References
- Wish JB. Assessing iron status: beyond serum ferritin and transferrin saturation. Clin J Am Soc Nephrol. 2006;1 Suppl 1:S4-S8. doi:10.2215/CJN.01490506
Frequently asked questions
What is Transferrin Saturation?
Calculates transferrin saturation from serum iron and total iron binding capacity. Assessment of iron deficiency or overload in adults, with ferritin and blood count.
How is the result calculated?
TSAT (%) = serum iron (µg/dL) / total iron binding capacity (µg/dL) × 100.
How should the result be interpreted?
Laboratory index used to estimate iron availability for erythropoiesis and recognize overload.
What are the sources?
Wish JB. Assessing iron status: beyond serum ferritin and transferrin saturation. Clin J Am Soc Nephrol. 2006;1 Suppl 1:S4-S8.