BiomarkersTransferrin saturation
Blood & iron
Transferrin saturation
How full your iron carriers are
On your report it may say: TSAT, % saturation
Transferrin saturation shows what percentage of your iron-carrying protein is loaded with iron. It helps tell iron deficiency apart from iron overload.
Typical ranges · %
Calculated: serum iron ÷ TIBC × 100
Repeated results above 45% are a reason to check for iron overload.
Ranges vary by lab, age and sex. The range printed on your report applies.
If it's low
Too little iron is available for making red blood cells.
Common causes
- Iron deficiency
- Inflammation
What you might notice
- Tiredness
- Breathlessness
If it's high
Carriers are very full, which can suggest iron overload.
Common causes
- Hereditary haemochromatosis
- Excess iron supplements
- Liver disease
What you might notice
- Joint pain
- Fatigue
- Often none early on
Testing
- Who should test
- With a full iron panel.
- How to prepare
- Morning, fasting test, no iron supplements for 24 hours.
- When to retest
- With your iron panel.
What can help
Food sources
See a doctor if it's repeatedly above 45%.
Common questions
Is this the same as ferritin?
No. Ferritin is storage; saturation is what's in transit.
Why does inflammation matter?
It traps iron in storage and lowers saturation.
Explore further
Related markers
When to take them
Sources
Free nutrition assessment
Not sure what your body needs?
Answer a few questions about your diet, lifestyle and goals, and SYNC builds a personalised supplement plan with the reason for every suggestion. Free, about 6–8 minutes.
Build My Nutrition PlanFor general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.