Comparison of reticulocyte hemoglobin equivalent with traditional markers of iron and erythropoiesis in pediatric dialysis.

BACKGROUND: Anemia is a major complication for patients on chronic dialysis. Erythropoietin is effective if iron is available, however unnecessary iron supplementation results in iron overload. Reticulocyte hemoglobin equivalent (Ret-He) may be useful for assessing iron status. METHODS: A national retrospective cohort study including all children on chronic dialysis in New Zealand between 2007 and 2013, pairing Ret-He with demographic information, anemia indices, and markers of iron status. RESULTS: In 606 observations, we found a modest relationship between Ret-He and transferrin saturation (TSAT) (r = 0.34, p < 0.001) and a poor correlation between Ret-He and ferritin (r = 0.09, p = 0.04). There was a negative correlation between ferritin and hemoglobin (r = -0.14, p = 0.002), a weak positive correlation between TSAT and hemoglobin (r = 0.12, p = 0.007), and a modest positive correlation between Ret-He and hemoglobin (r = 0.22, p < 0.001). The diagnostic performance of Ret-He to detect absolute iron deficiency (cut-off value 28.9 pg, sensitivity 90 %, specificity 75 %, AUC 0.87) was good. CONCLUSIONS: Ret-He is a more relevant marker of iron status than ferritin and TSAT. This supports prospectively testing Ret-He to distinguish between iron deficiency and suboptimal erythropoietin dosing as competing causes for anemia. Ferritin is an unhelpful biomarker of iron deficiency in this setting.