RESUMO
The value of soluble transferrin receptor (sTfR) detected in serum is closely related to erythroid TfR turnover rate. An increased erythropoietic activity causes an increase in the sTfR level. Therefore, it is a useful test for monitoring the erythropoiesis. In this study, a new immunoturbidimetric method for automated measurement of sTfR was evaluated for its performance characteristics. Imprecision studies on patients' sera with 1.01 mg/l and 2.94 mg/l concentrations yielded within-run CVs of 1.16% and 1.27%. Accuracy analysis of the test by using the low and high control kit sera with 1.45 mg/l and 5.41 mg/l concentrations were 89.06% and 95.41%, respectively. The evaluation was also performed in 60 individual pediatric subjects, 30 beta-thalassemia/HbE and 30 control pediatric subjects. There is a statistically significant difference of sTfR between both groups (p < 0.0005, 95% Cl = 9.457-14.124). Ninety-five percent of matched pediatric subjects had sTfR level < or = 2.670 mg/l and 93.33% of patients diagnosed beta-thalassemia/HbE had values > 2.670 mg/l. In conclusion, this immunoturbidimeteric test yields good laboratory performance characteristics in terms of precision and accuracy.