Institute of Clinical Chemistry and Biochemistry, University Medical Centre Ljubljana, Ljubljana, Slovenia.
Clin Chem Lab Med. 2010 Oct;48(10):1427-32. doi: 10.1515/CCLM.2010.287. Epub 2010 Aug 13.
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.
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.
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.
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.
非转铁蛋白结合铁（NTBI）是自由基损伤的有力促进剂，对生物系统具有高度毒性，导致蛋白质、脂质和 DNA 的氧化损伤。
该测定法基于螯合剂氮川三乙酸（NTA）与血清 NTBI 的结合，并通过生化分析仪用铁嗪试剂试剂盒测定超滤液中的 Fe-NTA 络合物。为了测定极低浓度的 NTBI，修改了血清铁测定的程序参数。
线性度高达 15μmol/L，分析回收率为 93%-103%。检测限为 0.076μmol/L。在浓度为 0.338、1.717 和 5.916μmol/L 时，批内变异系数分别为 2.37%、1.23%和 0.812%。在 14 名赛艇运动员样本中，运动后测量的 NTBI 浓度在所有样本中均显著升高。在年龄较大的运动员中，运动前后的 NTBI 浓度中位数（范围）分别为 0.197（-0.11 至 0.58）和 3.353（2.39-8.97）μmol/L，在年龄较小的运动员中，分别为 0.197（-0.18 至 1.17）和 1.360（0.47-2.49）μmol/L。
通过对血清铁测定的描述性修改，可以用高灵敏度和特异性来测量 NTBI。所提供的数据是该测定法适用性的说明性示例。
