Considerations for the use of the reticulocyte hemoglobin equivalent in daily practice

Abstract

The reticulocyte hemoglobinequivalent(Ret-He) measured by some hematological autoanalyzers provides the amount of hemoglobin present in reticulocytes. It reflects hemoglobin synthesis in hematological precursors, corresponding to the hemoglobinization of the last 48-72hours. It correlates with iron deficient erythropoiesis, so it became an effective auxiliary tool to identify iron deficiency (ID) and to diagnose iron deficiency anemia (IDA). Our objective was to evaluate the usefulness of Ret-He for the study of anemias and to determine the best cut-off for the diagnosis of IDA, as well as to analyse optimal cut-off for ID screening. We analyzed 213 patients, who were classified as without anemia(Sin-A,n:80), microcytic anemia(MiA,n:64), normocytic anemia(NA,n:59) and macrocytic anemia (MaA,n:10). Of the 213 patients, 112 had requests for other parameters of iron availability and were classified as iron deficiency (ID,n:54) and non-iron deficiency(NO-ID,n:47). The mean value(±1DE) of Ret-He(pg) was 31.48(±1.81), 21.15(±3.66), 29,07(±4.32) y 37.49(±5.08) for Sin-A, AMi, AN y AMa y 22.35(±4.72) y 31.25(±1.89) para ID y No-IDrespectively. The only group that did not show significant differences with Sin-Awas No-ID(p<0.05). Receiver operator characteristic (ROC) curve analysis shows that Ret-He has similar performance to transferrin saturation (area under the curve (AUC):0.95 and 0.96respectively) and superior to ferritin (AUC:0.90) and to mean corpuscular volume (AUC:0.88).The Cut-off with best sensitivity (S) and specificity (E) was 28.45pg(S/E:87.04/89.36%). Ret-HE<28.05pg (E:95.74% and S:81.48%) has high E for ID while Ret-He>29.90pg discards ID(S:94.44%), retaining an acceptable E(82.98%).