RESUMO
Introduction:The soluble form of transferrin receptor (sTfR) has been pointed as a useful parameter to assess the iron status and erythropoiesis activity. Immature reticulocytes present high concentration of membrane transferrin receptor. We tested the correlation between sTfR and reticulocyte parameters in iron deficiency anemia (IDA) and heterozygous beta-thalassemia (hetero beta-thal) patients. Laboratory parameters related to iron status and reticulocytes were studied in order to establish their clinical value to distinguish both anemias. Material and Methods: Reticulocyte measurements were obtained using a semi-automated analyzer and serum concentration of sTfR was determined by an immunoenzymatic technique. Forty-nine IDA and 43 hetero beta-thal patients were studied. Results: Reticulocyte count and sTfR values were significantly higher in IDA than in hetero beta-thal group, but the best parameter to distinguish both anemias was sTfR index, obtained by the ratio sTfR/ferritin level. Transport compartment was better evaluated by transferrin dosage than by transferrin iron binding capacity (TIBC) determination. The association of serum iron with transferrin measurements (transferrin index) improved the accuracy of the transferrin test. Discussion: The correlation between highly immature reticulocytes and sTfR level was observed only in IDA group, suggesting that cellular iron deprivation is the main responsible factor for up regulation of the sTfR synthesis in immature red blood cells. High sTfR values in hetero beta-thal patients reflect a degree of ineffective erythropoiesis in this hemoglobinopathy. Conclusion: We concluded that sTfR, ferritin and transferrin measurements are useful and precise parameters to discriminate IDA from hetero beta-thal patients
