Transferrin saturation (TSAT) is calculated as serum iron divided by TIBC, expressed as a percentage. It represents the proportion of iron-binding sites on transferrin that are occupied by iron.

Low transferrin saturation (< 20%) is the most sensitive early marker of iron-deficient erythropoiesis — the point at which insufficient iron reaches the bone marrow for red blood cell production. High transferrin saturation (> 45%) may indicate iron overload and is the recommended screening test for hereditary hemochromatosis.

Transferrin saturation provides more actionable information than serum iron alone because it accounts for the body's compensatory increase in transferrin production during deficiency.

What It Measures

Percentage of transferrin binding sites occupied by iron, calculated from serum iron and TIBC.

Reference Ranges

How GATOR Tracks This

Related Biomarkers