RESUMO
Soluble transferrin receptors have gained interest in the field of diagnosing anemias. Reference ranges differ according to the method used for the quantification of sTfR. We aim to explore the distributional properties and diagnostic performance of sTfR in pre-school healthy children as well as in children with beta-thalassemia carriers, iron deficiency with normal hematological phenotype (ID) and iron deficiency anemia (IDA). Circulating sTfR as well as biochemical and hematological indices were determined in 521 pre-school children and four groups (normal children, beta-thalassemia traits, ID and IDA) were formed. Diagnostic performance and distribution of sTfR according to age and in relation to several parameters were evaluated in every group. Three hundred eighty one children (261 normal, 60 beta-thalassemia traits, 44 ID and 16 IDA) aged 1-6 years were included. We found that distribution of sTfR differed significantly among the four groups (Kruskal Wallis p<0.001) with children in the normal group exhibiting lower concentrations compared to all other. A negative correlation between sTfR and age occurred in the normal (beta=-0.12, p<0.001) and the ID groups (beta=-0.13, p=0.035). In the beta-thal and IDA groups sTfR is correlated to HbA(2) (beta=0.34, p=0.001) and ferritin (Spearman's rho=-0.6, p=0.014) respectively. An area under the curve equal to 0.63 was achieved by sTfR in distinguishing between normal and ID children. Sensitivity and specificity were 70.5% and 50% respectively at a cut-off of 2.5 mg/l. Levels of sTfR are negatively correlated to age in pre-school children while dyserythropoietic procedures like beta-thal, ID, and IDA significantly affect them. These findings indicated that the accuracy of sTfR in diagnosing ID from normal children is limited. Standardization will allow the use of formulas that combine sTfR and ferritin which are of greater diagnostic value than sTfR alone.
