MEASURING PLASMA FERRITIN LEVELS WITH TWO DIFFERENT METHODS: A COMPARISON OF ROCHE COBAS E601 VERSUS ROCHE COBAS C501 (INTEGRATED MODULAR SYSTEM ROCHE COBAS 6000)

Background: The aim of our study is to compare plasma ferritin levels found to be high or low in terms of reference range by means of electrochemiluminescence (ECLIA) and immunoturbidimetric method and to examine whether they can be used interchangeably. Methods: 84 patients with high plasma ferritin level and 153 patients with low ferritin level according to the reference range were included in the study. Plasma samples measured in Cobas e601 device with ECLIA were also measured as immunoturbidimetric Cobas c501 device. For method comparison, CLSI EP-A3 Guideline was used. While the consistency between the methods were specified with Passing-Bablok regression analysis and Spearman correlation analysis, bias error between the methods (bias%) was determined through Bland-Altman analysis. Results: Both high and low plasma ferritin levels measured with Cobas e601 module and determined high in terms of reference range were compared with the results found with cobas c501 module. The difference was found to be statistically significant (p<0.001). According to regression and correlation (for low plasma ferritin levels; r: 0.993, p<0.001, for high plasma ferritin levels; r: 0.966, p<0.001) results, the methods were in consistency with each other. Additionally, while the bias% value was found to be 10.4% for low plasma ferritin levels, it was found to be 12.6% for high ferritin levels. Conclusions: Accordingly, we believe that, comparison with more samples especially in terms of different clinical decision levels is required in order to examine interchangeable use of immunoturbidimetric method in integrated devices and ECLIA.