Diagnostic Utility Of Hemoglobin And Reticulocyte Parameters For Iron Deficiency In Children With Cyanotic Congenital Heart Disease: A Systematic Review

Chronic hypoxemia and compensatory erythrocytosis complicate the interpretation of hematological parameters in children with cyanotic congenital heart disease (CCHD). The diagnostic utility of hemoglobin and reticulocyte-related parameters for assessing iron deficiency in this population remains uncertain. This review aimed to evaluate the diagnostic accuracy of hemoglobin and reticulocyte parameters for detecting iron deficiency in children with established CCHD. Two studies involving 169 children were included. Hemoglobin and hematocrit showed limited discrimination for iron deficiency, with area under the receiver operating characteristic curve (AUC) values of 0.57 and 0.61, respectively. Reticulocyte hemoglobin content (CHr) and reticulocyte hemoglobin equivalent (Ret-He) demonstrated better performance, with AUC values of 0.74-0.83. At cut-offs around 28 pg, sensitivity ranged from 64.3% to 75.0% and specificity from 84.1% to 88.9%. Red cell distribution width (RDW) showed potential, with 91.5% specificity, while a combined CHr-RDW model achieved an AUC of 0.794 and an accuracy of 85.4% in one study. Reticulocyte percentage performed poorly (AUC 0.47). CHr and Ret-He may complement conventional investigations for iron deficiency in children with established CCHD, whereas hemoglobin and hematocrit have limited discriminatory value. The evidence remains limited by the small number of studies, heterogeneous diagnostic criteria, and lack of external validation. Larger prospective studies with age-specific thresholds and appropriate comparison groups are needed.