Reticulocyte hemoglobin equivalent (Ret He) and assessment of iron-deficient states

Abstract

Direct measurement of the reticulocyte hemoglobin content provides useful information for the diagnosis and treatment of iron-deficient states. We have examined direct measurements of reticulocyte and red cell hemoglobin content on the Sysmex XE 2100 (Ret He and RBC He respectively) and the Bayer ADVIA 2120 (CHr and CH respectively) analyzers. Good agreement was found between Ret He and CHr (Y = 1.04X - 1.06; r2= 0.88) and between the RBC He and CH parameters (Y = 0.93X + 1; r2= 0.84 n = 200) in pediatric patients and in normal adults (Ret He and CHr; Y = 1.06X - 0.43; r2= 0.83; n = 126; RBC He and CH; Y = 0.94X + 1; r2= 0.87; n = 126). In 1500 blood samples from patients on chronic dialysis, Ret He was compared with traditional parameters for iron deficiency (serum iron <40 microg/dl, Tsat <20%, ferritin <100 ng/ml, hemoglobin <11 g/dl) for identifying iron-deficient states. Receiver operator characteristic (ROC) curve analysis revealed values of the area under the curve for Ret He of 0.913 (P < 0.0001). With a Ret He cutoff level of 27.2 pg, iron deficiency could be diagnosed with a sensitivity of 93.3%, and a specificity of 83.2%. Ret He is a reliable marker of cellular hemoglobin content and can be used to identify the presence of iron-deficient states.

Figure 1

Method comparison data, XE 2100 and ADVIA 2120: top, Ret He vs. CHr; bottom RBC He vs. CH. Data were obtained from 200 clinical samples and show good correlation between the Ret He and ADVIA CHr (Y = 1.04X − 1.06; r² = 0.88) and between the RBC He and ADVIA CH (Y = 0.93X + 1; r² = 0.84).

Figure 2

Method comparison data, XE 2100 and ADVIA 2120: top, Ret He vs. CHr; bottom RBC He vs. CH. Data were obtained from 126 normal adults, and show good correlation between the Ret He and ADVIA CHr (Y = 1.06 − 0.43; r² = 0.83; n = 126) and between the RBC He and ADVIA CH (Y = 0.94X + 1; r² = 0.87; n = 126).

Figure 3

In the top panel, the difference between Ret He and CHr is plotted vs. the mean value for the two parameters. In the bottom panel, the difference between RBC He and CH is plotted vs. the mean value for the two parameters. Data were combined for the 200 clinical samples and the 126 normal controls.

Figure 4

Top: ROC curve analysis for Ret He and the diagnosis of iron-deficiency anemia in hemodialysis patients. The diagnostic performance of Ret He in identifying iron-deficient states was compared with that of traditional parameters for iron deficiency (serum iron <40 μg/dl, Tsat <20%, ferritin <100 ng/ml, hemoglobin <11 g/dl). By using a Ret He cutoff level of 27.2 pg, iron deficiency could be diagnosed with a sensitivity of 93.3%, and a specificity of 83.2%. The area under the curve was 0.913. Bottom: ROC curve analysis for Ret He and the diagnosis of functional iron deficiency in hemodialysis patients. Functional iron deficiency was defined tests as Tsat <20%, Ferritin 100–800 ng/ml, and HGB <11 g/dl. The diagnostic performance of ret He is less favorable (area under the curve 0.657).