NOTE: A transferrin index is also described for carbohydrate deficient transferrin associated with ethanol abuse (see above).
transferrin index =
= (serum iron in µmol/L) / (serum transferrin in µmol/L)
Interpretation:
• A transferrin index > 1.0 indicates increased iron stores as seen in hemochromatosis.
Benefits over transferrin saturation (iron divided by TIBC):
(1) The precision of the transferrin assay is better than that of TIBC.
(2) High ferritin levels may be associated with interference in the TIBC assay.
Molecular weight for transferrin: There seems to be several different values used.
(1) Tietz uses 89,000 daltons (Clinical Guide to Laboratory Tests, Third Edition)
(2) The Sigma catalogue gives a range of 76,000 – 81,000.
(3) Beilby et al encountered a range from 76,500 to 99,000, with 76,500 and 88,000 as the most commonly used by laboratories. He used 79,570 based on MacGillivray et al, J Biol Chem, 1983; 258: 3543-3553.
|
Molecular Weight
|
1 mg/dL converts to
|
|
76,500
|
0.1307 µmol/L
|
|
79,570
|
0.12567 µmol/L
|
|
81,000
|
0.1234567 µmol/L
|
|
88,000
|
0.1136 µmol/L
|
|
89,000
|
0.1124 µmol/L
|
