In February 1997, a panel of medical experts convened by the
CDC recommended that transferrin saturation (TS) be used as the
initial diagnostic test for hereditary hemochromatosis.
The most frequently used method for determining TS requires an
assay of serum iron and the total iron-binding capacity (TIBC)
of serum proteins.
Serum iron is a measure of circulating iron bound to transferrin
and reflects total body iron. Because serum iron measurements
may be affected by menstrual cycle, time of day, diet,
hepatitis, and use of iron containing placebos found in some
oral contraceptive packages, serum iron levels alone are not
sensitive indicators of iron status.
The major iron-binding and transport protein in serum is
transferrin, although small amounts of iron may be bound to ferritin,
albumin, and other proteins or compounds.
Transferrin levels, along with serum iron levels as part of the
TIBC test, are useful in the differential diagnosis of many
disorders, including hemochromatosis (Witte DL, 1996).
Transferrin saturation (TS) can be determined by two common
Note: Few laboratory order forms will have TS category lines.
Ordering serum iron and a TIBC will allow for the calculation of
TS. If TIBC is not an option, order serum iron and UIBC.
- Measurement of TIBC. TS = (serum iron/TIBC x 100).
- Sum of measured
unsaturated iron-binding capacity (UIBC) and measured serum
TS = (serum iron/ [serum iron + UIBC] x 100).
forms are not standard. Ordering iron (cpt 83540) will not
result in the calculation of transferrin saturation. Make sure
to check the box for both iron & tibc (cpt 83550). Some labs use
iron and uibc. Serum ferritin may be ordered at the same time
and is often listed as ferritin, serum (cpt 82728).