In Utero Iron Status and Auditory Neural Maturation in Premature Infants as Evaluated by Auditory Brainstem Response

Abstract

Objective-To determine if cord ferritin (CF) concentration, an index of in utero iron status, is associated with auditory neural maturation in premature infants.Study design-A prospective cohort study was performed to compare auditory neural maturation between infants with latent iron deficiency (CF 11-75 ng/ml) and infants with normal iron status (CF > 75 ng/ml) at birth. Our inclusion criteria were 27-33 weeks gestational age infants admitted to the Neonatal Intensive Care Unit between July, 2007 and November, 2008 within 12 hours after birth and had cord blood collected. Infants with TORCH infections, chromosomal disorders, craniofacial anomalies, culture proven sepsis, and/or unstable conditions were excluded. CF concentrations were measured using a chemiluminescence immuno-assay method. Bilateral monaural auditory brainstem evoked responses (ABR) were performed using 80 dB nHL click stimuli at a repetition rate of 29.9/sec within 48 hours after birth.Results-Of 80 infants studied, 35 infants had latent iron deficiency. After controlling for confounders, infants with latent iron deficiency had significantly prolonged absolute wave latencies I, III, and V and decreased frequency of mature ABR waveform compared with infants with normal iron status. Conclusion-Premature infants with in utero latent iron deficiency have abnormal auditory neural maturation compared with infants with normal in utero iron status. KeywordsAuditory brainstem evoked response; latent iron deficiency; cord ferritin; brain development Iron is crucial for fetal brain development and substantial iron accretion occurs during the last trimester of pregnancy.(1-5) Although there is active transport of iron across the placenta, several clinical conditions are known to negatively affect fetal iron status including severe Corresponding Author: Sanjiv B Amin, MD, MS, Department of Pediatrics, PO Box 651, 601 Elmwood Avenue, Rochester, NY -14642, Tel: 585-275-2972, Fax: 585-461-3614, Sanjiv_Amin@urmc.rochester.edu. Edited by AJ and WFB Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access METHODSA prospective cohort study comparing auditory neural maturation of premature infants with latent iron deficiency (CF 11-75 ng/ml) with premature infants with normal iron status (CF > 75 ng/ml) was conducted. We chose a cord ferrtin concentration of 75 ng/ml as a cut off level to define latent iron deficiency because this cut-off level has been used by previous studies and was shown to be associated with neurodevelopment outcomes in term and premature infants.(15,17) Parental consent was obta...

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