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Total iron-binding capacity of blood serum

Medical expert of the article

Dr. Maor Lahav

Gastroenterologist

Alexey Kryvenko, medical expert
Last reviewed: 05.07.2025

Total iron-binding capacity of blood serum is an indicator of transferrin concentration. It should be taken into account that when assessing the transferrin content based on the results of determining the total iron-binding capacity of blood serum, it turns out to be overestimated by 16-20%, since at more than half saturation of transferrin, iron binds to other proteins. The total iron-binding capacity of blood serum is not the absolute amount of transferrin, but the amount of iron that can bind to transferrin. By subtracting the amount of serum iron from the total iron-binding capacity of blood serum, the unsaturated, or latent iron-binding capacity is determined: unsaturated iron-binding capacity = TIBC - serum iron. Normally, the unsaturated iron-binding capacity of blood serum averages 50.2 mmol/L (279 μg/dL).

Reference values (norm) of total iron-binding capacity of blood serum

Age	Reference values of TIBC
Age	Mcg/dl	µmol/l
Children under 2 years old	100-400	17.90-71.60
Children over 2 years old and adults	250-425	44.75-76.1

Based on the determination of iron in the blood serum and the total iron-binding capacity of the blood serum, the saturation coefficient is calculated (the ratio of serum iron to the total iron-binding capacity of the blood serum, expressed as a percentage). Normally, this coefficient fluctuates from 16 to 54, averaging 31.2.

Calculation formula: saturation coefficient = (serum iron/TIBC)×100.