10. Henry RJ. Clinical chemistry, principles and technics, 1st ed. New York:

serum iron concentration or UIBC value is below detect-able limits, TIBC cannot be determined. In conclusion, TIBC values determined by DTIBC assay were strongly correlated with TRF concentrations. The slope of the regression line for the DTIBC values plotted against the TRF is consistent with the theoretical TIBC/ TRF ratio. TIBC values calculated from the sum of serum iron and UIBC were significantly lower than those ob-tained by the DTIBC assay. This can be attributed to underestimation of UIBC values by the colorimetric assay. UIBC is an independent factor that influences the differ-ence between the converted TIBC values and the calcu-lated TIBC values. We suggest that TIBC be measured by direct TIBC methods and that UIBC be calculated as the difference between TIBC and serum iron