Effects of intrauterine latent iron deficiency on auditory neural maturation in full-term newborns

Iron Deficiency Prior to Discharge in Very Low Birth Weight Infants: Screening with Reticulocyte Hemoglobin Content

OBJECTIVE

This study aimed to assess the iron status prior to discharge in very low birth weight (VLBW) infants utilizing reticulocyte hemoglobin content (CHr) and evaluate the impact of delayed cord clamping (DCC) on iron status.

STUDY DESIGN

This is a retrospective analysis of VLBW infants from two tertiary level of care Neonatal Intensive Care Units. The primary outcome was the proportion of VLBW infants with low CHr (<29 pg) prior to discharge. Hematologic parameters were also compared between infants who received or did not receive DCC. Infants with a positive newborn screen for hemoglobin Bart's were excluded.

RESULTS

Among the 315 infants included, 99 infants (31.4%) had low CHr prior to discharge. The median (interquartile range) CHr prior to discharge was 30.8 pg (28.4-39 pg). DCC was performed in 46.7% of infants. Hemoglobin at birth, discharge, and CHr prior to discharge were higher and the need for blood transfusion and the number of infants with low CHr prior to discharge were lower in the DCC group.

CONCLUSION

Approximately 31.4% of VLBW infants had low CHr near the time of discharge suggesting they were iron deficient. DCC improved hematological parameters prior to discharge in VLBW infants. CHr content can be used to guide iron supplementation in VLBW infants to potentially improve their iron status and long-term neurocognitive outcomes.

KEY POINTS

· DCC was associated with an improved hemoglobin and iron status at discharge in VLBW infants.. · CHr is an early and reliable marker for iron deficiency.. · Approximately one in three VLBW infants can be iron deficient at the time of discharge..

Lower iron stores were associated with supoptimal gross motor scores in infants at 3-7 months

Aim

To investigate associations between iron status and gross motor scores in infants aged 3–7 months.

Methods

In a prospective study, 252 infants aged 3–7 months were examined using the age‐standardised Alberta Infant Motor Scale (AIMS) prior to analysing iron status in 250 infants. Combined AIMS and ferritin results were assessed in 226 infants, whereas AIMS and reticulocyte haemoglobin (ret‐Hb) results were obtained for 61 infants. We used logistic regressions and receiver operator characteristics to analyse our data.

Results

With AIMS z‐score <10th percentile as outcome measure, optimal cut‐off value for ferritin was 51 μg/L (sensitivity 86%, specificity 81%) and 28 pg for ret‐Hb (sensitivity 86%, specificity 85%). The area under the curve for ferritin and ret‐Hb was 0.886 and 0.896, respectively (n = 61). Ferritin <51 μg/L predicted an AIMS z‐score <10th percentile in a logistic regression (OR 3.3, 95% CI 1.4–7.5, p = 0.006, n = 226). Six of 14 (43%) infants with ret‐Hb <28 pg scored <10th percentile on AIMS compared to 1/47 (2.1%) infants with ret‐Hb ≥28 μg/L (Exact, p < 0.001).

Conclusion

Reticulocyte haemoglobin of <28 pg and ferritin <51 μg/L were associated with suboptimal gross motor scores in infants 3–7 months.

Neonatal thyrotropin levels and auditory neural maturation in full-term newborns

Objective

This study aimed to look for a possible relationship between thyrotropin (TSH) values from neonatal bloodspot screening testing and newborn lower auditory pathway myelinization evaluated using the brainstem evoked response audiometry (ABR) test.

Methods

Sixty-two healthy full-term newborns without perinatal problems were enrolled in the study. TSH results were collected from neonatal bloodspot screening data and were below the test cut-off level (15μUI/mL). The TSH test was performed between three and seven days, and the ABR test was performed in the first 28 days of life. The newborns were divided into two groups: Group 1 (n = 35), TSH between 0 and 5μUI/mL, and group 2 (n = 27), TSH between 5 and 15μUI/mL. Data are presented as mean ± SD, median, or percentage, depending on the variable.

Results

Wave latency and interpeak interval values for Groups 1 and 2 were as follows: Wave I: 1.8 ± 0.1 and 1.7 ± 0.1; Wave III: 4.4 ± 0.1 and 4.4 ± 0.1; Wave V: 6.9 ± 0.1 and 6.9 ± 0.1; interval I–III: 2.6 ± 0.1 and 2.6 ± 0.1; interval I–V: 5.1 ± 0.1 and 5.1 ± 0.1; interval III–V: 2.4 ± 0.1 and 2.4 ± 0.1. There were no significant differences in ABR parameters between groups 1 and 2 (p > 0.05). Multiple regression analysis showed a slight significant negative correlation between TSH and wave I values (standardized β = −0.267; p = 0.036), without observing any relationship with the other ABR waves recorded.

Conclusions

This study investigated the relationship of TSH and auditory myelinization evaluated by ABR. It did not show a significant change in lower auditory pathway myelinization according to TSH levels in newborns with TSH screening levels lower than 15 μUI/mL.

Iron deficiency in infancy: current insights

PURPOSE OF REVIEW

Iron deficiency is the most common micronutrient deficiency and infants are at particular risk. The purpose of this review is to summarize recent studies that explored the metabolism of iron in infants as well as the risks and benefits of iron supplementation in different populations.

RECENT FINDINGS

The ability of infants to regulate iron homeostasis is not fully known but most likely different from adults. Reducing iron deficiency has beneficial effects on neurodevelopment but iron overload may have adverse functional effects including diarrhea and even poor neurodevelopment. Recent studies have confirmed benefits of delayed cord clamping and supplementation of infants in risk groups while iron supplementation to pregnant women has shown limited effect in the offspring with regard to iron status and neurodevelopment. Further support is given to the recommendation that exclusive breast feeding, without supplementation, is safe for normal birth weight infants until 6 months whereafter an iron-rich diet should be given.

SUMMARY

Iron deficiency negatively impacts global health but efforts to identify optimal interventions are progressing. Yet, questions remain, particularly regarding long-term risks, benefits and optimal interventions for low birth weight infants as well as the level of iron fortification in infant formula.

Prevalence and Utility of Low Mean Corpuscular Volume in Infants Admitted to the Neonatal Intensive Care Unit

OBJECTIVE

To determine the prevalence of low mean corpuscular volume (MCV) in newborn infants admitted to the neonatal intensive care unit and to assess low MCV as a diagnostic test for alpha thalassemia.

STUDY DESIGN

Retrospective analysis of all infants admitted to the neonatal intensive care unit between January 2010 and October 2018 for which a complete blood count was performed during the first 3 postnatal days. Infants with a low MCV were compared with those with a normal MCV. Infants with positive hemoglobin Bart (Hb Bart) were compared with those withnegative Hb Bart. Low MCV was also evaluated as a diagnostic test for alpha thalassemia.

RESULTS

A total of 3851 infants (1386 preterm, 2465 term) met the inclusion criteria and 853 (22.2%) had a low MCV. A low MCV was more common in term (25%) compared with preterm infants (17.1%, P < .001). Hb Bart positive newborn screening was identified in 133 infants (3.5%). Hb Bart was positive in 11.1% of infants with low MCV compared with 1.3% with normal MCV (P < .001). The sensitivity, specificity, positive predictive value, and negative predictive value of low MCV for the diagnosis of alpha thalassemia were 71.4%, 79.6%, 11.3%, and 98.7%, respectively.

CONCLUSIONS

As Hb Bart positive newborn screens were seen in only 11.1% of infants with microcytosis, further diagnostic investigation may be warranted in individual infants. Further research to correlate microcytosis with iron status in infants and mothers is needed as well as studies using DNA analysis for the evaluation of alpha thalassemia variants.

The Role of Iron in Brain Development: A Systematic Review

One-third of children falter in cognitive development by pre-school age. Iron plays an important role in many neurodevelopmental processes, and animal studies suggest that iron sufficiency in pregnancy and infancy is particularly important for neurodevelopment. However, it is not clear whether iron deficiency directly impacts developmental outcomes, and, if so, whether impact differs by timing of exposure or developmental domain. We searched four databases for studies on iron deficiency or iron supplementation in pregnancy, or at 0-6 months, 6-24 months, or 2-4 years of age. All studies included neurodevelopmental assessments in infants or children up to 4 years old. We then qualitatively synthesized the literature. There was no clear relationship between iron status and developmental outcomes across any of the time windows or domains included. We identified a large quantity of low-quality studies, significant heterogeneity in study design and a lack of research focused on pregnancy and early infancy. In summary, despite good mechanistic evidence for the role of iron in brain development, evidence for the impact of iron deficiency or iron supplementation on early development is inconsistent. Further high-quality research is needed, particularly within pregnancy and early infancy, which has previously been neglected.