Assessment of iron sufficiency in premature infants treated with darbepoetin using conventional and novel erythrocyte metrics.

OBJECTIVE: Randomized trials demonstrate that administering darbepoetin to extremely low birth weight (ELBW) neonates increases hematocrits and reduces or eliminates transfusions. However, further studies are needed regarding maintaining adequate iron during darbepoetin therapy. STUDY DESIGN: We analyzed datasets from the Neonatal Research Network Darbe Trial and Intermountain Health to assess iron sufficiency during darbepoetin treatment. We tracked traditional markers of erythropoiesis (reticulocytes and RET-He), and novel markers of iron-limited erythropoiesis (Micro-R and HYPO-He). RESULTS: Among the placebo recipients, RET-He fell over the first week (33.6 ± 0.5 pg to 27.4 ± 0.2 pg, p < 0.001). Darbepoetin recipients fell further (p < 0.0001). We identified a reciprocal relationship between rising reticulocytes and falling RET-He. The majority (83%) of darbepoetin recipients with a RET-He <25 pg had Micro-R and HYPO-He measurements indicating iron-sufficiency. CONCLUSIONS: Traditional and novel red cell markers together may better inform iron sufficiency during accelerated erythropoiesis.