Plasma proteins in acute and chronic lung disease of the newborn

Use of Albumin in the NICU: An Evidence-based Review

Albumin is the most abundant protein in human blood with distinctive functions throughout the human body. Low albumin levels are a predictor of mortality as well as disease outcome in children and adults. However, the clinical significance of hypoalbuminemia and the role of albumin infusions in NICUs remain unclear and controversial.

Gestational Age-Dependent Reference Ranges for Albumin Levels in Cord Serum

BACKGROUND

To diagnose hypoalbuminemia in newborns, it is essential to establish a definition applicable to those with a different gestational age (GA) and clinical conditions. A positive correlation between serum albumin levels and GA has been reported, but the study was limited to small numbers of newborns. We therefore investigated the GA-dependent reference ranges for serum albumin levels using cord venous blood (UC-Alb levels) from a large number of newborns delivered at a tertiary perinatal center.

METHODS

Albumin levels were assessed in 2,917 newborns at 22-41 weeks of GA after exclusion of those with congenital disorders. Linear regression analysis was used to correlate GA and UC-Alb levels. After calculation of the percentile values of UC-Alb levels for each week of GA, the distributions were approximated by the least-squares method. To validate the determined linear approximation of the 5%ile value, the UC-Alb levels in newborns with hydrops fetalis and gastroschisis were used.

RESULTS

A significant positive correlation between GA and UC-Alb levels was found (rs = 0.701, p < 0.001, respectively). The distribution of the 5%ile of UC-Alb levels (Y) by GA (X) was approximated as a straight line (Y = 0.062 × X + 0.326, R2 = 0.951). Among the 59 and 18 newborns with hydrops fetalis and gastroschisis, 51 (86.4%) and 15 (83.3%), respectively, were below the line.

CONCLUSIONS

We established GA-dependent reference ranges for serum albumin levels, which may be useful to accurately diagnose hypoalbuminemia in newborns.

Maternal-Neonatal Serum Albumin Level and Neonatal Respiratory Distress Syndrome in Late-Preterm Infants

Background: To determine the correlation between maternal-neonatal serum albumin level and respiratory distress syndrome (RDS) in late-preterm infants. Methods: This case-control study included 112 late-preterm newborns admitted to the neonatal intensive care unit of our hospital between January 2018 and July 2019. Those infants were divided into the RDS group (n = 56) and the non-RDS group (n = 56). Levels of maternal-neonatal serum albumin, pregnancy complications, and baseline information of the infants were compared between the two groups. Results: 1. There was no correlation between maternal and neonatal serum albumin measures. The maternal albumin level in the RDS group was lower than that in the control group (33.38 ± 3.31 vs. 33.60 ± 3.31, P > 0.05), but the difference was not statistically significant. The neonatal albumin level in the RDS group was significantly lower than that in the control group (32.70 ± 2.48 vs. 35.66 ± 3.27, P < 0.05). To predict RDS in late-preterm infants, using the albumin cutoff level of 34 g/L provides a sensitivity of 83.9% with a specificity of 62.5%. 2. Gestational age, primipara, placenta previa, antenatal corticosteroid therapy, delivery mode, and neonatal serum albumin level were associated with RDS in the late-preterm infant. 3. After adjustment for gestational age, logistic regression analysis showed that neonatal serum albumin level, placenta previa, and delivery mode were independent risk factors for RDS in late-preterm infants. However, albumin level did not related to the severity of RDS. Conclusion: The decrease in serum albumin within the first day after birth was closely related to the occurrence of RDS in late-preterm infants.

Serum iron concentration is a useful biomarker for assessing the level of inflammation that causes systemic symptoms in bovine acute mastitis similar to plasma haptoglobin

The aim of present study was to evaluate the precision of plasma haptoglobin (HPT), serum iron (Fe) and plasma transferrin (Tf) concentrations as biomarkers of the severity of acute mastitis (AM) in cows. Fourteen Holstein Friesian cows with AM were divided into severe (n=8) and mild groups (n=6) based on systemic and local inflammation, and 12 healthy cows were also enrolled as controls. As a result, significant changes were observed in plasma HPT and serum Fe concentrations. The proposed cut-off points for plasma HPT and serum Fe concentrations for the severity of AM in cows based on receiver operating characteristic analyses were >10.3 µg/ml and <49.0 µg/dl, respectively. No significant difference was observed in the plasma Tf concentration.

Uses and misuses of albumin during resuscitation and in the neonatal intensive care unit

Albumin is one of the most abundant proteins in plasma and serves many vital functions. Neonatal concentrations vary greatly with gestational and postnatal age. In critically ill neonates, hypoalbuminemia occurs due to decreased synthesis, increased losses or redistribution of albumin into the extravascular space, and has been associated with increased morbidities and mortality. For that reason, infusion of exogenous albumin as a volume expander has been proposed for various clinical settings including hypotension, delivery room resuscitation, sepsis and postoperative fluid management. Albumin is often prescribed in infants with hypoalbuminemia, hyperbilirubinemia, and protein-losing conditions. However, the evidence of these practices has not been reviewed or validated. Albumin infusion may initiate highly complex processes that vary according to the individual and disease pathophysiology. Indeed, it may be associated with harms when misused. In this review, we critically appraise the scientific evidence for administering albumin in most conditions encountered in the neonatal intensive care unit, while emphasizing the benefits and risks associated with their use.

Oncotic pressure and paediatric cardiopulmonary bypass: establishing baseline data for complex congenital cardiac surgery and its relation to risk stratification

Objectives:

Colloid osmotic pressure (COP) is a major determinant of fluid shift in paediatric patients undergoing corrective surgery for congenital heart disease (CHD) using cardiopulmonary bypass (CPB). However, very few baseline data are available for those patients requiring surgery within the first few weeks and months of life. Our aim was to determine if our CHD population exhibited COP similar to that of other extremely ill subsets of patients and, if so, whether this related to risk stratification model scores.

Methods:

Thirty consecutive patients under 10 kg underwent cardiac surgery with CPB. Data were collected on COP, albumin concentration, prime composition, post-operative length of ventilation and intensive care unit (ICU) stay as well as risk stratification utilising Risk Adjustment for Congenital Heart Surgery (RACHS-1) and Partial Risk Adjustment in Surgery (PRAiS) scoring systems.

Results:

The patients had a mean pre-bypass COP of 13.9±2.5 mmHg. A significant negative correlation was observed between pre-operative baseline COP and length of ventilation (r=0.7; p<0.001) and a significant negative correlation between PRAiS (r=0.64; p<0.001) and RACHS-1 (r=0.5; p=0.004) scores and baseline COP was seen.

Conclusions:

Neonatal and paediatric patients requiring surgical correction of complex congenital cardiac malformations exhibit extremely low baseline COP, comparable to other sick neonatal populations, and are lower than those previously reported. Baseline COP correlates significantly with predicted survival rates and time spent on a ventilator.

Low Plasma Protein Levels at Birth Are Associated with Poor Cardiovascular Adaptation and Serious Adverse Outcome in Infants with Gestational Age <32 Weeks: The ProHémie Study

BACKGROUND

Retrospective studies suggest that early hypoproteinemia has prognostic value for adverse outcome in preemies, but the underlying pathophysiology is unknown. We hypothesized that the prognostic relevance of hypoproteinemia could be related to its association with impaired cardiovascular function and organ perfusion during transition.

OBJECTIVES

To describe the plasma protein status and the measures of cardiovascular function according to the outcome in infants <32 weeks' gestation.

METHODS

One hundred and twenty-eight infants were prospectively included from birth to discharge. During the first 24 h of life, we assessed the cardiovascular function and systemic and organ blood flow by Doppler ultrasound, and monitored cerebral and renal regional oxygen saturation (cRSO2, rRSO2) using near-infrared spectroscopy. These measures were analyzed in relationship to hypoproteinemia (total plasma protein level <40 g/L at 12 h of life) and severe adverse outcome (death or survival with severe neurological injury).

RESULTS

Hypoproteinemia was associated with a higher risk of a severe adverse outcome after adjustment of confounding variables (adjusted OR = 6.8; 95% CI 1.3-34). Compared to normoproteinemic infants and after adjustment for gestational age, hypoproteinemic ones had more significantly: hypotension (7 vs. 13%, p = 0.03), abnormal capillary refilling time (20 vs. 36%, p < 0.001), abnormal renal blood flow (resistive index 0.78 ± 0.11 vs. 0.85 ± 0.09, p = 0.04), lower rRSO2 (82.9 ± 9.2 vs. 73.6 ± 10.5%, p = 0.04), and lower systemic vascular resistance (0.155 ± 0.058 vs. 0.108 ± 0.037 mm Hg/L/kg; p = 0.04). The cRSO2 patterns were significantly decreased in infants with severe adverse outcome and independent from protein status.

CONCLUSION

Hypoproteinemia is associated with impaired cardiovascular function. Further studies are required to elucidate the interplay between changes in protein levels, postnatal hemodynamics and clinical outcome.

Association of Serum Albumin Level and Mortality in Premature Infants

BACKGROUND

Hypoalbuminemia has been proven to be a powerful predictor of mortality in adult patients. However, prognostic value of serum albumin in neonates is not clear.

OBJECTIVE

To assess the relationship between serum albumin level within the first day of life and outcome in preterm infants born before 32 weeks of gestation.

METHODS

The study was conducted prospectively in Baskent University Hospital between October 2008 and November 2009. Patients were divided by gestational age into two groups as below or of 28 weeks and above 28 weeks. Then serum albumin percentile groups were established within each gestational age group and were defined as <25, 25-75, and >75 percentile groups by combining percentile groups between the two gestational age groups. Three serum albumin percentile groups were compared regarding neonatal outcomes.

RESULTS

A total of 199 infants with mean birth weight of 1,272 ± 390 g and mean gestational age of 29.2 ± 2.2 weeks were admitted to the study. The mean serum albumin level was 30.6 ± 4.7 g/l for all patients. The mean serum albumin levels were 25.5 ± 3.8, 30.1 ± 2.7, and 35.3 ± 3.7 g/l for <25, 25-75, and >75 percentile groups, respectively. Prevalence of infants with respiratory distress syndrome and prevalence of infants with sepsis and mortality were significantly higher in <25 percentile group. Logistic regression analysis showed that serum albumin <25 percentile and birth weight were independent predictive variables of mortality. Albumin concentrations lower than 27.2 g/l was associated with mortality, with a sensitivity of 71% and a specificity of 86%.

CONCLUSION

Low serum albumin level within the first day of life is an independent predictor of mortality in preterm infants.

The effect of maximum storage on iron status, oxidative stress and antioxidant protection in paediatric packed cell units

BACKGROUND

Premature babies may receive multiple transfusions during the first weeks of their life. Strong associations exist between the receipt of blood transfusions and the development of the major consequences of prematurity such as retinopathy and chronic lung disease. The possible physiological link between the receipt of blood and disease is unclear, but iron-induced oxidative damage and/or bacterial colonisation would promote these conditions. Premature babies are poorly equipped to deal with any increases in iron and oxidative load that they may acquire via blood transfusions. To determine whether there are any relationships between these factors, we studied iron and oxidative status of just expired (i.e. 36 days old) paediatric red blood cell (RBC) packs.

MATERIALS AND METHODS

Just expired paediatric RBC packs were obtained from the local blood bank. The extracellular medium surrounding the RBC was separated by centrifugation and the following parameters measured: total iron concentration, total iron binding capacity, non-transferrin-bound iron [NTBI], haemoglobin, total and reduced ascorbate, and malondialdehyde concentration.

RESULTS

The extracellular fluid of the paediatric packs (n =13) was rich in iron, a high percentage of which (36%) was present as potentially toxic NTBI. It was highly redox active with limited antioxidant protection and iron-binding capacity.

DISCUSSION

The extracellular medium surrounding packed RBC could potentially be toxic if administered to patients with limited iron sequestering and antioxidant capacity, such as premature babies. Further studies are required to determine at what point during storage these changes become potentially harmful so that clinical studies can examine the optimal storage time for blood destined for premature babies.

Iron homeostasis in the neonate

The regulation of the availability of micronutrients is particularly critical during periods of rapid growth and differentiation such as the fetal and neonatal stages. Both iron deficiency and excess during the early weeks of life can have severe effects on neurodevelopment that may persist into adulthood and may not be corrected by restoration of normal iron levels. This article provides a succinct overview of our current understanding of the extent to which newborns, particularly premature newborns, are able (or not able) to regulate their iron status according to physiologic need. Postnatal development of factors important to iron homeostasis such as intestinal transport, extracellular transport, cellular uptake and storage, intracellular regulation, and systemic control are examined. Also reviewed are how factors peculiar to the sick and premature neonate can further adversely influence iron homeostasis and exacerbate iron-induced oxidative stress, predispose the infant to bacterial infections, and, thus, compromise his or her clinical situation further. The article concludes with a discussion of the areas of relative ignorance that require urgent investigation to rectify our lack of understanding of iron homeostasis in what is a critical stage of development.

Plasma biomarkers of oxidative stress: relationship to lung disease and inhaled nitric oxide therapy in premature infants

OBJECTIVES

Inhaled nitric oxide treatment for ventilated premature infants improves survival without bronchopulmonary dysplasia. However, there has been no information regarding possible effects of this therapy on oxidative stress. We hypothesized that inhaled nitric oxide therapy would not influence concentrations of plasma biomarkers of oxidative stress.

PATIENTS AND METHODS

As part of the Nitric Oxide Chronic Lung Disease Trial, we collected blood samples at specified intervals from a subpopulation of 100 infants of <1250 g birth weight who received inhaled nitric oxide (20 ppm, weaned to 2 ppm) or placebo gas for 24 days. Plasma was assayed for total protein and for 3-nitrotyrosine and carbonylation by using immunoassays.

RESULTS

The demographic characteristics and primary outcome for the infants were representative of the entire group of infants who were in the Nitric Oxide Chronic Lung Disease Trial. For all infants at baseline, before receiving study gas, the concentration of total protein was inversely correlated with the respiratory severity score, and plasma carbonyl was positively correlated with severity score, supporting an association between oxidative stress and severity of lung disease. Infants who survived without bronchopulmonary dysplasia had 30% lower protein carbonylation concentrations at study entry than those who had an adverse outcome. At each of 3 time points (1-10 days) during exposure to study gas, there were no significant differences between control and treated infants for concentrations of plasma protein, 3-nitrotyrosine, and carbonylation.

CONCLUSIONS

Inhaled nitric oxide treatment for premature infants who are at risk for bronchopulmonary dysplasia does not alter plasma biomarkers of oxidative stress, which supports the safety of this therapy.

Renal impact of fluid management with colloids: a comparative review

BACKGROUND AND OBJECTIVES

Colloids such as hydroxyethyl starch (HES), gelatin, dextran and albumin are useful for maintaining renal perfusion and function. The comparative renal effects of colloids have not been previously reviewed.

METHODS

Computer searches of the MEDLINE and EMBASE bibliographic databases and the Cochrane Library were conducted using the search terms: colloids; hetastarch; gelatin; dextrans; serum albumin; kidney failure; cardiac surgical procedures; and kidney transplantation. Relevant studies were also sought through hand searching and examination of reference lists. Results of identified studies were qualitatively summarized with account taken for potential confounding factors.

RESULTS

The three artificial colloids HES, gelatin and dextran all exhibited troublesome renal side-effects. Randomized trials have demonstrated adverse renal effects of HES in sepsis and surgery. Undesirable renal effects are common to all available HES solutions regardless of molecular weight, substitution or C2/C6 ratio. While some of its effects may be less severe than those of HES, gelatin also can adversely affect the kidney. A negative renal impact of dextran is well-established, although this colloid is now less extensively used than formerly. As the normal endogenous colloid, albumin exhibits a wide margin of renal safety, although albumin overdose needs to be avoided. Albumin also appears to exert protective effects on the kidney such as inhibition of apoptosis and scavenging of reactive oxygen species.

CONCLUSIONS

Colloids display important differences in their actions on the kidney. These contrasting renal effects should be considered in making fluid management decisions.

Is there a causal relationship between the receipt of blood transfusions and the development of chronic lung disease of prematurity?

The number and total volume of blood transfusions received by premature babies is, after gestational age and birth weight a good predictor of the likelihood of developing chronic lung disease of prematurity (CLD) and retinopathy of prematurity (ROP). Oxidative damage, inflammation and pulmonary infections are also strongly associated with the development of CLD. It is currently not clear whether there is a causal relationship between the receipt of blood transfusions and oxidative damage, infection, inflammation and CLD in these babies. Strong arguments may be made both for and against a causal relationship. The babies who receive blood transfusions are usually smaller than those who do not, and are ventilated, often with high oxygen levels, for a longer period of time. The longer the baby is on a ventilator the more likely it is to develop pulmonary infection and inflammation. All these factors will promote free radical production and oxidative damage irrespective of the receipt of blood transfusion. This would argue against a causal relationship. On the other hand, an argument may be presented which is based on iron promoted free radical generation, infection and fibrosis consequent to the breakdown of haeme released from transfused erythrocytes. Haeme is broken down by haeme oxygenase (HO) to iron, CO and bilirubin. Under normal circumstances the products of HO activity are beneficial to the organism, but when HO activity is excessive, the products are potentially damaging. Free iron, (in the Fe2+ form) if not sequestered with protein or urate, will generate highly toxic free radicals via the Fenton and Heber-Wiess reactions, predispose the tissue to infection and promote fibrosis. The iron chelating ability of the premature baby appears to be limited so that it would be difficult to deal with any increase in free iron production. Free iron will in turn induce HO activity leading to a potentially serious positive feedback process. The lung is particularly sensitive to iron induced HO activity. In addition, HO activity may be enhanced by other events occurring in the premature lung such as the production of proinflammatory cytokines and the reduced level of glutathione. Thus, the possibility of a causal relationship clearly exists and needs to be examined. This can be attempted by measuring the products of HO activity in relation to the receipt of blood transfusions.

Low plasma retinol concentrations increase the risk of developing bronchopulmonary dysplasia and long-term respiratory disability in very-low-birth-weight infants

BACKGROUND

The effect of inadequate vitamin A during the neonatal period on lung status is still unknown.

OBJECTIVE

We tested the hypothesis that low plasma retinol concentrations during the first month of life are independently associated with bronchopulmonary dysplasia (BPD) and long-term respiratory morbidity at 6 mo gestationally corrected age (ie, the age the infant would be had the pregnancy gone to term).

DESIGN

Respiratory outcome information was obtained to 6 mo corrected age for a historical cohort of very-low-birth-weight neonates (<1250 g) who were admitted to intensive care over a 7-y period. Neonates with one or more plasma measurements of retinol concentrations < 0.35 micromol/L (<100 microg/L) on days 1-28 were classified as having low vitamin A. BPD was defined at day 28 by clinical and radiologic criteria and by use of supplemental oxygen at 36 wk postmenstrual age (PMA). Dependence on supplemental oxygen was used to identify long-term respiratory disability at 6 mo corrected age. Multivariate logistic regression analyses were conducted.

RESULTS

Of the 350 study infants, 192 (55%) had low vitamin A status. BPD occurred in 52% of survivors at day 28 (173/331) and at 36 wk PMA (147/285). Fourteen percent (33/244) required oxygen support at 6 mo corrected age. Adjusted odds ratios of BPD with low vitamin A were 3.5 (95% CI: 1.7, 7.2) at day 28 and 1.7 (1.0, 2.7) at 36 wk PMA. At 6 mo corrected age, the adjusted odds ratio was 2.6 (1.1, 6.4) for respiratory disability with low vitamin A.

CONCLUSION

Poor vitamin A status during the first month of life significantly increased the risk of developing BPD and long-term respiratory disability.

Vitamin A and Bronchopulmonary Dysplasia: Research, Issues, and Clinical Practice

Vitamin A is a crucial antioxidant for preterm infants because it protects the lungs from oxidative damage induced by the administration of supplemental oxygen. Although all preterm infants are born with smaller vitamin A stores than full-term infants, the store of vitamin A in preterm infants at risk for bronchopulmonary dysplasia (BPD) is often especially deficient. Despite the increases in plasma vitamin A concentrations that have been achieved with vitamin A supplementation, only modest improvements in clinical outcomes and incidence of BPD have been noted in this population. This article reviews the research on vitamin A supplementation for preterm infants, as well as the issues and clinical implications associated with this intervention.

Non-protein-bound iron and free radical damage in fetuses with rhesus haemolytic disease: influence of intrauterine transfusions

OBJECTIVE

To determine iron-induced free radical damage in fetal rhesus haemolytic disease (RHD) before and after repeated intrauterine red blood cell transfusions and its relation to hydrops fetalis.

DESIGN

Prospective, observational study.

SETTING

Department of Obstetrics, Leiden University Medical Centre, the Netherlands.

POPULATION

Fifty anaemic fetuses, including 13 hydropic ones, 9 preterm and 12 term neonates and 8 female non-pregnant adults.

METHODS

Venous blood plasma samples were collected from 50 fetuses suffering from RHD preliminary to the first, and if appropriate, subsequent intrauterine red blood cell transfusions for determination of iron status including non-protein-bound iron (NPBI) and iron-binding primary antioxidant proteins, total plasma anti-oxidant capacity and its contributing secondary antioxidants (e.g. vitamin C, uric acid, sulphydryl groups and peroxidation products). Results were compared with values of healthy preterm and term neonates directly at birth and adult controls. Within the fetal haemolytic group, 13 hydropic fetuses were analysed as a separate group.

MAIN OUTCOME MEASURES

Non-protein-bound iron, antioxidants, total antioxidant capacity and peroxidation products. Sub analysis of the outcome measures of the hydropic fetuses.

RESULTS

RHD fetuses had at initial cordocentesis a significantly higher NPBI level and a significantly lower total plasma antioxidant capacity than control babies and adults. Their vitamin C tended to be more oxidised but lipid peroxidation had not increased, when compared with preterm babies. The repeated intrauterine red blood cell transfusions had a positive effect on the total antioxidant capacity of plasma and did not increase the concentration of NPBI. The hydropic fetuses, who had higher NPBI concentrations and lower plasma protein concentrations and total antioxidant capacity, did not show more peroxidation products in plasma than the non-hydropic fetuses. Fetuses without reversal of hydrops despite intrauterine transfusions showed decreasing levels of proteins with subsequent transfusions but peroxidation products remained constant.

CONCLUSION

Repeated intrauterine red blood cell transfusions do not lead to free radical damage in the fetus in utero. Iron-induced free radical activity does not appear to play a causative role in the proceeding of hydrops fetalis in RHD.

Albumin infusion for low serum albumin in preterm newborn infants

BACKGROUND

Intravenous albumin infusion to treat hypoalbuminaemia is used in intensive care nurseries. Hypoalbuminaemia occurs in a number of clinical situations including prematurity, the acutely unwell infant, respiratory distress syndrome (RDS), chronic lung disease (CLD), necrotising enterocolitis (NEC), intracranial haemorrhage, hydrops fetalis and oedema. Fluid overload is a potential side effect of albumin administration. Albumin is a blood product and therefore carries the potential risk of infection and adverse reactions. Albumin is also a scarce and expensive resource.

OBJECTIVES

The primary objective was to assess whether albumin infusions, in preterm neonates with low serum albumin, reduces mortality and morbidity. A secondary objective was to assess whether albumin infusion is associated with significant side effects.

SEARCH STRATEGY

Searches were made of MEDLINE from 1966 to April 2004, CINAHL from 1982 to April 2004 and the current Cochrane Central Register of Controlled Trials (CENTRAL, The Cochrane Library issue 1, 2004). Previous reviews (including cross references) and abstracts were also searched.

SELECTION CRITERIA

All randomised controlled trials in which individual patients were allocated to albumin infusion versus control were included. Cross-over studies were excluded. Quasi randomised trials were excluded. Participants were preterm infants who had hypoalbuminaemia. Types of interventions included albumin infusion versus placebo (e.g. crystalloid) or no treatment.

DATA COLLECTION AND ANALYSIS

The reviewers worked independently to search for trials for inclusion and to assess methodological quality. Studies were assessed using the following key criteria: blinding of randomisation, blinding of intervention, completeness of follow up and blinding of outcome measurement.

MAIN RESULTS

Only two small studies were found for inclusion in this review and only one reported clinically relevant outcomes - it found no significant differences for our primary outcome measure of death (RR 1.5 [95% confidence interval 0.3 - 7.43]) or secondary outcome measures of intraventricular haemorrhage, patent ductus arteriosus, necrotising enterocolitis, bronchopulmonary dysplasia, duration of mechanical ventilation and duration of oxygen therapy.

REVIEWERS' CONCLUSIONS

There is a lack of evidence from randomised trials to determine whether the routine use of albumin infusion, in preterm neonates with low serum albumin, reduces mortality or morbidity, and no evidence to assess whether albumin infusion is associated with significant side effects. There is a need for good quality, double-blind randomised controlled trials to assess the safety and efficacy of albumin infusions in preterm neonates with low serum albumin.

Neonatal iron nutrition

Preterm infants are prone to iron deficiency. Their total body iron content at birth is low and gets further depleted by clinical practices such as uncompensated phlebotomy losses and exogenous erythropoietin administration during the neonatal period. Early iron deficiency appears to adversely affect cognitive development in human infants. To maintain iron sufficiency and meet the iron demands of catch-up postnatal growth, iron supplementation is prudent in preterm infants. A dose of 2-4 mg/kg/day is recommended for preterm infants who are fed exclusively human milk. A dose of 6 mg/kg/day or more is needed with the use of exogenous erythropoietin or to correct preexisting iron deficiency. However, due to the poor antioxidant capabilities of preterm infants and the potential role of iron in several oxidant-related perinatal disorders, indiscriminate iron supplementation should be avoided.

Detection by ELISA of low transferrin levels in bronchoalveolar secretions of preterm infants

Transferrin levels in bronchoalveolar secretions (BAS) are very low compared to serum levels in humans. For the exact measurement of transferrin concentrations in BAS a very sensitive assay was developed as a double sandwich enzyme immunoassay using the combination of a polyclonal and a monoclonal antibody against human transferrin. The measurable range of the assay was 1.5 to 100 ng/ml of human transferrin. The lowest measurable value was 0.84 ng/ml and the sensitivity of the assay was 0.88 ng/ml. The coefficient of variation was 14.1% for 25 ng/ml (intra-assay) and 11-20% (inter-assay). The levels measured in 123 samples of BAS of preterm infants ranged between 0.03 and 8.93 (microgram/microgram secretory component (SC)). The determination of transferrin in BAS of preterm infants is helpful in determining oxidative damage, e.g. the availability of free iron, in the neonatal lung. The transferrin concentration in BAS of neonates who recovered from respiratory distress syndrome (RDS) in the first six days of life was 0.48 compared to 0.52 ((microgram/microgram SC), median range) for infants who developed chronic lung disease.