What this marker measures
Transferrin saturation is calculated by dividing serum iron by TIBC (×100 for percentage). Values below 15–20% suggest iron deficiency; values above 50–55% may suggest iron overload.
High or low: what it can mean
High TIBC
A high TIBC means the blood has excess transferrin capacity with little iron bound to it — a classic pattern in iron deficiency, where the body upregulates transferrin to capture more iron.
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Low TIBC
Low TIBC is seen in states of iron overload (all binding sites occupied) and also in inflammation, chronic disease, and malnutrition (where transferrin production decreases).
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Frequently asked questions
What is TIBC?
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TIBC measures the blood's maximum capacity to bind and carry iron. It reflects the amount of available transferrin — the protein that transports iron in the blood.
What does TIBC measure?
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Transferrin saturation is calculated by dividing serum iron by TIBC (×100 for percentage). Values below 15–20% suggest iron deficiency; values above 50–55% may suggest iron overload.
What does high TIBC mean?
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A high TIBC means the blood has excess transferrin capacity with little iron bound to it — a classic pattern in iron deficiency, where the body upregulates transferrin to capture more iron.
What does low TIBC mean?
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Low TIBC is seen in states of iron overload (all binding sites occupied) and also in inflammation, chronic disease, and malnutrition (where transferrin production decreases).
Related biomarkers
Editorial note
LabTestly explains lab markers using plain-English educational content. Reference ranges may vary by laboratory and should be interpreted with a clinician.
Educational content · Editorially reviewed for clarity · Last updated
Common sources used for lab-test education
Not medical advice
This page is for general understanding only and does not replace medical advice from your clinician. Reference ranges can vary by laboratory, age, sex, pregnancy status, medications, and clinical context.