Understanding increased ferritin levels in pediatric ECMO patients

Abnormally high serum ferritin levels have been reported during pediatric ECMO, attributed to frequent red blood cell transfusion and suggestive of iron overload. However, the utility of ferritin for diagnosing iron overload is complicated by its response as an acute-phase reactant. In this study, we aimed to assess the utility of ferritin for diagnosing ECMO-related iron overload, with secondary aims of understanding its relationship with inflammation and erythropoiesis. Ferritin was elevated in all pediatric ECMO runs (median 459 ng/ml, IQR = 327.3-694.4). While intermittent elevations in serum iron were observed, all normalized prior to decannulation. Unreported previously, erythropoietin (EPO) remained well above normative values prior to and throughout ECMO runs, despite frequent transfusion and exposure to hyperoxia. Ferritin correlated poorly with serum iron [r (80) = 0.05, p = 0.65], but correlated well with IL-6 [r(76) = 0.48, p < 0.001] and EPO [r(81) = 0.55, p < 0.001]. We suggest that serum ferritin is a poor biomarker of iron overload in ECMO patients, and that future investigation into its relationship with EPO is warranted.