transferrin saturation in percent =
= (((serum iron in µg/dL) / (total iron binding capacity in µg/dL)) * 100)
where:
• The units for serum iron and TIBC need to be the same. Conventional units are µg/dL. SIU are µmol/L.
Since (see next section):
calculated TIBC (in µg/dL) =
= 1.43 * (transferrin, in mg/dL)
This can be re-written as:
transferrin saturation in percent =
= 69.93 * (serum iron in µg/dL) / (serum transferrin in mg/dL)
where:
• 69.93 = 100 / 1.43
• According to Wu 1 mg of transferrin can bind 1.25 µg of iron rather than 1.43.
Interpretation
• lower limit of normal: greater than or equal to 16% (another source says 20%)
• upper limit of normal: 55%
Transferrin saturation is increased in conditions with iron overload:
(1) hemochromatosis
(2) hemosiderosis
(3) thalassemia
Transferrin saturation is decreased in:
(1) iron deficiency anemia
(2) anemia of chronic disease
