The influence of storage age on iron status, oxidative stress and antioxidant protection in paediatric packed cell units.

This interesting study examines the issue of “the storage lesion” in the critical setting of neonatal transfusion. It examines, in particular, the changes in iron and oxidative status of pediatric packed cell units occurring during their conservation from 3 days after donation up to the maximum recommended time of administration (35 days). This topic appears particularly relevant as the premature baby is poorly equipped to deal with an additional iron or oxidative load, being deficient in iron-binding capabilities and antioxidant defences.

The authors observed that both total iron and non-transferrin-bound iron (NTBI) were present in the extracellular fluid of pediatric packs on day 3 and rose almost linearly to maximal values at 35 days when 45.4% of the total iron was in the potentially highly toxic NTBI form. Interestingly, Hb and malondialdehyde (a robust marker of oxidative damage) increased more slowly over days 3 to 21 and then more steeply towards the end of the period of storage. Moreover, the study showed that reduced ascorbate, an important antioxidant which protects Hb against oxidative damage, remained relatively constant until around day 14 but, thereafter, it started to fall significantly, down to very low levels on day 35.

Altogether, the results of the study support the authors’ conclusion that during conservation a cycle of free radical-mediated damage may initiate and then further exacerbate iron release during storage which, in turn, may mediate further free radical-mediated cellular damage and that potential consequences to neonates who receive older stored blood may be significant. Although, as reported by the authors, a recent randomized controlled study in premature infants reported by Fergusson et al (JAMA 2012;308:1443-51) has not observed differences in outcome with regard to major consequences between a group of infants transfused with “fresh” blood (mean storage age = 5.1 days) and a group of babies transfused with older blood (mean storage age = 14.6 days), this study raises concerns on the appropriateness of utilizing pediatric packed cells units stored for longer than 21 days, and possibly more than 14 days, in such fragile patients and strongly supports the need for further studies in this setting.

– Giovanni Inghilleri