Comparison of two markers of iron sufficiency and neurodevelopmental outcomes

Background Iron deficiency during critical windows of brain development is associated with suboptimal neurodevelopmental outcomes. Identifying markers of neonatal iron status that best correlate with neurodevelopmental outcome is critical for optimal management of iron supplementation of neonates. Aims We aimed to evaluate two markers of iron sufficiency, ferritin and zinc protoporphyrin-to-heme ratios (ZnPP/H), with neurodevelopmental outcomes. Study design This is a retrospective cohort study. Subjects All infants with concurrent ferritin and ZnPP/H measurements obtained between October 2014 and April 2017 and Bayley Scales of Infant Development, 3rd Edition (BSID-III) evaluated at 24 months corrected age were included. Outcome measures Associations between iron markers (minimum, maximum and median ferritin and ZnPP/H) and BSID-III score at 24 months were assessed. Results 223 lab measurements from 62 infants were assessed. Mean gestational age was 28.1 weeks (SD = 2.6) with a mean birth weight of 1.1 kg (SD = 0.4). Significant associations between maximum and median ZnPP/H and motor score, and between median ZnPP/H and cognitive score were observed. Trends were also seen with higher minimum, median and maximum ZnPP/H associated with lower BSID-III scores, but did not reach statistical significance (p > 0.05). The associations between ferritin values and BSID scores were less consistent. Conclusions A positive association was seen between ZnPP/H values and BSID-III scores. Trends between ferritin and BSID values were less consistent, potentially because ferritin is more affected by inflammation. Consideration should be given to using ZnPP/H preferentially to adjust iron supplementation in the NICU to improve neurodevelopmental outcomes.