Utility of Reticulocyte Hemoglobin as a New Predictor of Anemia in Intensive Care Unit Patients

Manuel De La Cruz-Garcinuño ¹ Raúl Juárez-Vela ^2* Pablo Lasa-Berasain ³ Regina Ruiz De Viñaspre ^4* Michał Czapla, PhD, RD, EMT-P, FESC ⁵ Lourdes García-Muñoz ⁶ Enrique Polo-Andrade ⁶ Carmen Sarmiento ⁶ Javier Rodero-Martínez ⁶ Mirian Alonso-Arias ⁶ Saray López-Tornero ⁶ Manuel Quintana-Diaz ⁶

• ¹ Doctoral Program in Medicine and Surgery, Autonomous University of Madrid, Madrid, Madrid, Spain
• ² Grupac Research Group. Deparment of Nursing. University of La Rioja., Logroño, Spain
• ³ Intensive Care Unit, Complejo Hospitalario de Navarra, Pamplona, Navarre, Spain
• ⁴ Faculty of Health Sciences., University of La Rioja, Logroño, La Rioja, Spain
• ⁵ Wroclaw Medical University, Wrocław, Silesian, Poland
• ⁶ Intensive Care Unit, University Hospital La Paz, La Paz, Madrid, Spain

Introduction: Iron deficiency and anemia are common complications in critically ill patients, particularly in the Intensive Care Unit setting (ICU), where inflammation and infection are prevalent. Traditional markers like ferritin are unreliable in these contexts due to their behavior as acute-phase reactants. New hematimetric indices, such as Reticulocyte Hemoglobin Equivalent (RET-He) and Delta Hemoglobin Equivalent (Delta-He), may offer better predictive value for anemia in ICU patients. Objectives: This study aimed to evaluate the predictive utility of RET-He and Delta-He for anemia in critically ill patients and compare their performance with serum ferritin levels. Methods: A pilot, observational, prospective study was conducted on 40 ICU patients admitted for burns or polytrauma. Hematological and hematimetric parameters were analyzed at admission, 48 hours, 4 days, and 7 days post-admission. Mixed-effects regression models were used to assess the predictive value of RET-He, Delta-He, and ferritin for hemoglobin levels and anemia. Results: Significant reductions in hemoglobin and hematocrit were observed within the first 48 hours of ICU admission, while RET-He and Delta-He remained stable. Over 4 and 7 days, decreases in RET-He and Delta-He were strongly associated with lower hemoglobin levels and increased risk of anemia (p < 0.01). Ferritin levels did not predict anemia in either period. Conclusion: RET-He and Delta-He are valuable predictors of anemia in critically ill ICU patients, outperforming ferritin in this context. Their routine use could improve the early detection and management of iron deficiency and anemia in ICU settings.