Automated assay for non-transferrin-bound iron in serum samples.
BACKGROUND
Non-transferrin-bound iron (NTBI) is a powerful promoter of free radical damage and highly toxic to biological systems, resulting in oxidative damage to proteins, lipids and DNA.


METHODS
This assay is based on the binding of serum NTBI by the chelator nitrilotriacetic acid (NTA) and measurement of the ultrafiltrated Fe-NTA complex with the ferrozine reagent kit by a biochemical analyzer. To determine NTBI at extremely low concentrations, the program parameters for serum iron measurement were modified.


RESULTS
Linearity was up to 15 μmol/L with analytical recovery of 93%-103%. The limit of detection was 0.076 μmol/L. The within-run coefficient of variation was 2.37%, 1.23%, and 0.812% at concentrations of 0.338, 1.717, and 5.916 μmol/L, respectively. NTBI concentrations measured after exercise in samples obtained from 14 rowers, divided into two groups, were substantially higher in all samples. The median NTBI concentrations (range) before and after exercise were 0.197 (-0.11 to 0.58), and 3.353 (2.39-8.97) μmol/L, respectively, in older rowers and 0.197 (-0.18 to 1.17), and 1.360 (0.47-2.49) μmol/L, respectively, in younger rowers.


CONCLUSIONS
With the described modification for serum iron determination, NTBI can be measured with high sensitivity and specificity. The data presented are illustrative examples of the applicability of this assay.
Prezelj
Marija
M
Institute of Clinical Chemistry and Biochemistry, University Medical Centre Ljubljana, Ljubljana, Slovenia. marija.prezelj@kclj.si
Knap
Bojan
B
D000293:Adolescent; D000328:Adult; D001322:Autoanalysis; D001774:Blood Chemical Analysis / Q000295:instrumentation / Q000379:methods*; D005297:Ferrozine / Q000737:chemistry; D006801:Humans; D007501:Iron / Q000097:blood*; D007502:Iron Chelating Agents / Q000737:chemistry; D008297:Male; D009571:Nitrilotriacetic Acid / Q000737:chemistry; D012680:Sensitivity and Specificity; D014168:Transferrin; D055815:Young Adult
D007502:Iron Chelating Agents; D014168:Transferrin; D005297:Ferrozine; D007501:Iron; D009571:Nitrilotriacetic Acid