Diagnostic performance of reticulocyte hemoglobin equivalent in assessing the iron status

BACKGROUND: Measurement of reticulocyte hemoglobin equivalent (RET‐He) is rapid, convenient, and cost‐effective. Yet, researches on its performance in diagnosing iron deficiency with concurrent inflammation are limited. Hence, this study investigated RET‐He value in various states, including inflammation, and evaluated its diagnostic performance in iron status assessment. METHODS: Retrospectively, 953 clinical data and laboratory results—complete blood count, reticulocyte count, RET‐He, and serum ferritin—were reviewed. Patients on iron therapy were excluded. Iron status was defined by serum ferritin as the reference method. RET‐He among populations was investigated. Its diagnostic performance and optimal cutoff were determined by ROC analysis. RESULTS: Three population groups were classified: healthy control, iron deficiency anemia (IDA), and non‐ID anemia. Significantly, RET‐He value in IDA was lower than that of healthy control, anemia of inflammation, and chronic kidney disease (P < .0001). Low RET‐He was also observed in IDA with concomitant inflammation despite normal‐to‐high serum ferritin levels. No significant difference was observed between RET‐He values in pure IDA and thalassemia (P = .57). ROC curve analysis revealed AUC of 0.876 (P < .0001) at cutoff 30 pg, by which IDA was discriminated with 74.2% sensitivity and 97.4% specificity. Applying cutoff ≤30 pg, IDA can be diagnosed with 96% sensitivity, 97.4% specificity, 80% PPV, and 99.6% NPV. Hence, RET‐He >30 pg signifies a non‐IDA state. CONCLUSION: In addition to convenience and cost‐effectiveness, RET‐He cutoff >30 pg can be potentially used to exclude IDA due to its excellent diagnostic sensitivity and specificity.