Transferrin saturation
Blood cell systemAlso known as: TSAT, iron saturation, TfS
Transferrin saturation is the percentage of transferrin that is bound with iron.
It reflects how much of the transport protein is being used.
Why this matters
Transferrin saturation reveals whether your body has enough usable iron. Low saturation can indicate iron deficiency, which may lead to fatigue and impaired oxygen delivery, while high saturation may suggest iron overload, which can damage organs over time. Monitoring this marker supports timely dietary, lifestyle, or medical interventions to maintain healthy iron balance and overall metabolic function.
How this connects to other biomarkers
- Low Transferrin Saturation with low Ferritin and small red blood cells (microcytic anemia) confirms iron-deficiency anemia.
- High Transferrin Saturation (> 45%) with elevated Ferritin suggests iron overload (hereditary hemochromatosis); confirm with Liver Iron Content (LIC).
- Low Transferrin Saturation with normal or elevated Ferritin and high hs-CRP indicates anemia of chronic disease — the body has iron but inflammation is preventing it from being used.
How often should I test Transferrin saturation?
Most adults benefit from yearly transferrin saturation reassessment alongside serum iron and transferrin, as part of an iron panel. After iron supplementation or blood donation, retest the panel at 3 months.
At baseline / for screening: Once every 12 months from age 30 as part of an iron panel. More frequently, every 3 to 6 months, if you're a woman of reproductive age with heavy menstrual losses, vegetarian or vegan, or a regular blood donor.
When monitoring an intervention or change: Retest 3 months after starting or stopping iron supplementation, or after intravenous iron infusion. After blood donation or significant menstrual blood loss, allow 8 to 12 weeks for stores to begin recovering before retesting.
Included in
Ready to check your health?
Get a comprehensive view of your biomarkers with our advanced check-up packages.