Background The currently available various methods of estimation of total iron binding capacity (TIBC) show marked variation in reference range. Although serum transferrin (TF) level is a sensitive indicator of iron status, its measurement requires immunoassay equipment which may not be available in many routine biochemistry laboratories. So, this study was planned to find the most appropriate method to estimate TIBC. Objectives This study aimed to compare different methods of TIBC estimation and to corelate the TIBC values obtained by different methods with serum TF concentration. Material and Methods This analytical cross-sectional study was performed in the clinical chemistry laboratory of the Biochemistry Department of Medical College Baroda & SSG Hospital, Vadodara, Gujarat, on 250 leftover serum samples destined to be discarded. In all these samples, serum TIBC was estimated by direct method, indirect method, as well as calculated method (iron + unsaturated iron binding capacity [UIBC]) along with the measurement of serum TF level. Statistical Analysis Among the different methods, repeated analysis of variance (ANOVA) analysis and Bland-Altman plot were used to find out significance of difference. Correlation coefficients were found between different methods of TIBC estimation and serum TF levels. Results The means of TIBC by calculated, indirect, and direct methods were 344.51, 342.23, and 378.24 µg/dL, respectively. The mean of serum TF was 295.3 mg/dL. There was statistically significant difference between TIBC by direct and indirect methods and between direct and calculated methods. There was a strong positive correlation between TIBC by direct method and serum TF ( r = 0.888, p < 0.0001), but there was moderate correlation between TIBC by indirect method and serum TF ( r = 0.748, p < 0.04), and between TIBC by calculated method and serum TF ( r = 0.725, p < 0.05). Conclusion Among different methods of estimation of TIBC, direct method is more reliable in reference to serum TF levels.
Keywords: TIBC; iron status; serum transferrin.
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