Reference interval for calculated total iron-binding capacity using Olympus AU2700 analyzer

Total iron-binding capacity (TIBC) values are determined on Olympus AU2700 automated chemistry analyzer as the sum of serum iron and unsaturated iron-binding capacity (UIBC) - (calculated TIBC, TIBCcal). Considering that Olympus AU2700 automated analyzer was recently brought in function and TIBC values calculated from serum iron and UIBC values were significantly lower than those obtained by a direct and fully automated TIBC assay, it was necessary to determine the reference interval for TIBC, according to the recommendation that every laboratory should have its own reference ranges. The "calculation method" of TIBC determination showed satisfactory accuracy (p > 0.001) and precision, with CV values ranging from 0.91% to 1.63% within-run and from 2.30% to 2.80% day-to-day. The correlation between the TIBC values obtained with the "calculation method" using Olympus AU2700 analyzer (y) and those obtained with the direct method (x) was: y = 0.919x + 2.319 mmol/L (r = 0.980; Sy,x = 1.814; p < 0.001; N = 85). The reference interval for TIBC was determined using sera collected from 125 healthy individuals of both sexes, 15 to 80 years old. Since the values did not depend on sex, the reference interval calculated for the whole studied population ranged between 42.0 mmol/L and 64.3 mmol/L.