calculated transferrin (in mg/dL) =
= 0.7 * (TIBC, in µg/dL)
calculated TIBC (in µg/dL) =
= 1.43 * (transferrin, in mg/dL)
The use of SI units can alter these equations. The SI units for TIBC is µmole/L; the conversion factor from µg/dL is 0.179. The SI units for transferrin is g/L; the conversion factor from mg/dL is 0.01.
calculated TIBC in µmol/L =
= (transferrin in mg/L) * 0.025
According to Tietz (page 605), 1 mg transferrin can bind 1.25 µg of iron (assuming a MW for transferrin of 89,000; see below). With 1 mole of iron as 55.8 grams, 1.25 µg is 0.022 µmol/L. If a molecular weight of 79,500 is used, the factor of 0.025 is derived.
serum unsaturated iron binding capacity (UIBC) =
= ((TIBC in µg/dL) - (serum iron in µg/dL))
Alternative equation:
transferrin (mg/dL) =
= (0.8 * (TIBC in µg/dL)) - 43
Interpretation
TIBC increased:
(1) iron deficiency anemia
(2) acute and chronic blood loss
(3) acute liver damage
(4) late pregnancy
TIBC decreased:
(1) hemochromatosis
(2) cirrhosis
(3) thalassemia
(4) anemia of chronic disease
(5) nephrosis
