Not medically reviewed
Iron and vitamins
Transferrin saturation (TSAT)
Not medically reviewed · Content last updated · 1 min read ·
This is the date the draft was written, not a medical review date.
The percentage of transferrin binding sites occupied by iron, calculated as serum iron divided by TIBC multiplied by 100. It is a screening test for iron overload and, with ferritin, helps to define iron deficiency.
Reference interval
| Conventional (%) | SI (fraction) | |
|---|---|---|
| Adults | 20–50 % | 0.2–0.5 fraction |
Specimen: Serum (calculated: iron divided by TIBC) · Conventional × 0.01 = SI
Causes of high values
Iron overload (haemochromatosis, repeated transfusion, iron therapy), haemolytic and sideroblastic anaemias, liver disease, iron poisoning. A value above about 45 % in a fasting sample prompts further evaluation for haemochromatosis.
Causes of low values
Iron deficiency (typically below 16 to 20 %), anaemia of chronic disease and inflammation, chronic blood loss, malnutrition.
Pre-analytical and method notes
The usual range of about 20 to 50 % is wider in men than in premenopausal women, and thresholds for deficiency (commonly below 20 %) and for suspected overload (about above 45 %) depend on the guideline. Because it inherits the variability of serum iron, a fasting morning sample should be used and abnormal results repeated. Reference intervals vary by laboratory, method and population; use the interval printed on the report.
References
- Rifai N, Horvath AR, Wittwer CT. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Elsevier, 6th edition (2018) — Tier 3 (textbook)
- Loscalzo J, et al.. Harrison's Principles of Internal Medicine. McGraw-Hill, 21st edition (2022) — Tier 3 (textbook)
- Haemoglobin concentrations for the diagnosis of anaemia and assessment of severity (WHO/NMH/NHD/MNM/11.1). World Health Organization (2011) — Tier 1 (standards / international bodies)
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