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Iron Binding Capacity (TIBC)

Normal range: 250 – 450 µg/dL (higher is better)

TIBC measures how much iron your blood could carry if all its transferrin (the iron transport protein) were fully loaded. Think of it as the number of empty seats on the iron bus. When you are iron-deficient, your body makes more transferrin to capture every available iron molecule, so TIBC goes up. When iron is plentiful or inflammation is present, the body makes less transferrin, and TIBC drops.

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What can cause low TIBC?

A normal TIBC is 250 – 450 µg/dL. Higher is better.

High TIBC is the body's response to iron deficiency. The liver ramps up transferrin production to scavenge as much iron as possible. Pregnancy and oral contraceptive use also raise TIBC.

Low TIBC occurs in iron overload (hemochromatosis), chronic inflammatory conditions, liver disease, and malnutrition. The body makes less transferrin when iron is abundant or when protein production is impaired.

The same dietary and lifestyle factors that affect serum iron affect TIBC. Eating enough iron-rich foods, treating underlying blood loss, and managing chronic inflammation are the main levers. Oral contraceptives and estrogen therapy can raise TIBC, while chronic illness and malnutrition lower it.

TIBC (Total Iron Binding Capacity) measures how much iron your blood could carry if all its transferrin were fully loaded. Think of it as the number of empty seats on the iron bus. When you are iron-deficient, your body makes more transferrin to capture every available iron molecule, so TIBC goes up. When iron is plentiful, TIBC drops.

How does Iron binding capacity change with age?

Iron binding capacity stays relatively flat across adult ages (correlation with age, r = -0.04). Most of the spread in the chart below comes from differences between people rather than from age.

Iron binding capacity is stable with age, chart with median and linear trend

Biomarkers related to TIBC

TIBC is most highly correlated with Ferritin and Mean Corpuscular Hemoglobin. Here are the top biomarkers correlated with TIBC, based on 500,000 tests done by Empirical Health.

1 Ferritin
−27%
2 MCH
−20%
3 MCV
−18%
4 Triglycerides
+14%
5 Globulin
−11%
6 eVLDL
+11%
7 Sodium
−11%
8 HDL
+10%
9 ApoA1
+10%
10 Albumin
−10%

The percentage shows how strongly two biomarkers move together. A higher number means the relationship is stronger. Green = rises and falls together. Orange = one rises as the other falls.

Frequently asked questions about TIBC

TIBC test cost

TIBC comes in an iron panel (about $30–$65). Empirical's $190 panel adds Ferritin, Iron, and 100+ other biomarkers.

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Where to test TIBC

You can measure your TIBC for at 2,200+ testing locations across the US. Click below and enter your zip code to browse locations near you.

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