Normal Iron Saturation Range
The normal range for transferrin saturation (TSAT) is 20-50% in adults. 1
Standard Reference Values
- TSAT of 20-50% represents the normal range for iron saturation in healthy adults 1
- Values below 20% indicate iron deficiency or iron-deficient erythropoiesis in the general population 2, 1, 3
- Values above 50% suggest iron overload or iron-replete status 1
Clinical Context Matters
The interpretation of TSAT varies based on clinical circumstances:
In Chronic Kidney Disease
- Target TSAT is ≥20% to support adequate erythropoiesis 2, 1
- Absolute iron deficiency is defined as TSAT <20% with ferritin <100 ng/mL 2
- Some evidence suggests maintaining TSAT between 30-50% may optimize anemia management in hemodialysis patients receiving erythropoietin 4
In Cancer Patients
- TSAT <20% with ferritin <30 ng/mL defines absolute iron deficiency 2, 1
- TSAT between 20-50% with ferritin 30-800 ng/mL defines functional iron deficiency 2, 1
In Pregnancy and General Population
- TSAT <20% indicates iron deficiency requiring evaluation 3
- In children aged 0.5-12 years, TSAT <16% suggests iron deficiency only when accompanied by anemia and low mean corpuscular volume 5
Critical Interpretation Principles
TSAT must always be interpreted alongside ferritin and hemoglobin, never in isolation 1, 6:
- Inflammation falsely lowers TSAT while elevating ferritin, making TSAT more reliable than ferritin alone in inflammatory conditions 1
- TSAT <20% does not mandate treatment unless accompanied by low ferritin or anemia 1
- TSAT >20% does not exclude functional iron deficiency in patients receiving erythropoiesis-stimulating agents, as pharmacological stimulation of erythropoiesis can create functional deficiency despite adequate stores 2, 1
Common Pitfalls
- Do not rely on TSAT alone—ferritin levels provide complementary information about iron stores 6
- In acute or chronic inflammatory states, ferritin becomes an acute-phase reactant and may be falsely elevated; TSAT becomes the more reliable marker 2, 1
- A TSAT of 20% is not an absolute discriminator—some patients above this threshold remain functionally iron deficient, particularly those on erythropoietin therapy 2, 4