Prebiotics in the management of pediatric gastrointestinal disorders: Position paper of the ESPGHAN special interest group on gut microbiota and modifications.

Prebiotics are substrates that are selectively utilized by host microorganisms conferring a health benefit. Compared to probiotics there are few studies with prebiotics in children. Most studies have been performed using infant formula supplemented with prebiotics, while add-on prebiotic supplementation as prevention or treatment of childhood gastrointestinal disorders has rarely been reported. The aim of this position paper was to summarize evidence and make recommendations for prebiotic supplementation in children with gastrointestinal diseases. Recommendations made are based on publications up to January 1, 2023. Within the scope of the European Society for Paediatric Gastroenterology Hepatology and Nutrition Special Interest Group on Gut Microbiota and Modifications, as in our previous biotic recommendations, at least two randomized controlled clinical trials were required for recommendation. There are some studies showing benefits of prebiotics on selected outcomes; however, we cannot give any positive recommendations for supplementing prebiotics in children with gastrointestinal disorders.

Reevaluating the FDA's warning against the use of probiotics in preterm neonates: A societal statement by ESPGHAN and EFCNI.

The recent advisory issued by the United States Food and Drug Administration, cautioning against the routine administration of probiotics in preterm neonates, has sparked a lively debate within the scientific community. This commentary presents a perspective from members of the Special Interest Group on Gut Microbiota and Modifications within the European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) and other authors who contributed to the ESPGHAN position paper on probiotics for preterm infants, as well as representatives from the European Foundation for the Care of Newborn Infants. We advocate for a more nuanced and supportive approach to the use of certain probiotics in this vulnerable population, balancing the demonstrated benefits and risks.

Exhaled Volatile Organic Compounds for Early Prediction of Bronchopulmonary Dysplasia in Infants Born Preterm.

OBJECTIVE(S): To investigate the predictive performances of exhaled breath volatile organic compounds (VOCs) for development of bronchopulmonary dysplasia (BPD) in infants born preterm. METHODS: Exhaled breath was collected from infants born <30 weeks' gestation at days 3 and 7 of life. Ion fragments detected by gas chromatography-mass spectrometry analysis were used to derive and internally validate a VOC prediction model for moderate or severe BPD at 36 weeks of postmenstrual age. We tested the predictive performance of the National Institute of Child Health and Human Development (NICHD) clinical BPD prediction model with and without VOCs. RESULTS: Breath samples were collected from 117 infants (mean gestation 26.8 ± 1.5 weeks). Thirty-three percent of the infants developed moderate or severe BPD. The VOC model showed a c-statistic of 0.89 (95% CI 0.80-0.97) and 0.92 (95% CI 0.84-0.99) for the prediction of BPD at days 3 and 7, respectively. Adding the VOCs to the clinical prediction model in noninvasively supported infants resulted in significant improvement in discriminative power on both days (day 3: c-statistic 0.83 vs 0.92, P value .04; day 7: c-statistic 0.82 vs 0.94, P value .03). CONCLUSIONS: This study showed that VOC profiles in exhaled breath of preterm infants on noninvasive support in the first week of life differ between those developing and not developing BPD. Adding VOCs to a clinical prediction model significantly improved its discriminative performance.

Probiotics for the Management of Pediatric Gastrointestinal Disorders: Position Paper of the ESPGHAN Special Interest Group on Gut Microbiota and Modifications.

BACKGROUND: Probiotics, defined as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host, are widely used despite uncertainty regarding their efficacy and discordant recommendations about their use. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Special Interest Group on Gut Microbiota and Modifications provides updated recommendations for the use of probiotics for the management of selected pediatric gastrointestinal disorders. METHODS: All systematic reviews and/or meta-analyses, as well as subsequently published randomized controlled trials (RCTs) (until December 2021), that compared the use of probiotics in all delivery vehicles and formulations, at any dose, with no probiotic (ie, placebo or no treatment), were eligible for inclusion. The recommendations were formulated only if at least 2 RCTs on a similar well-defined probiotic strain were available. The modified Delphi process was used to establish consensus on the recommendations. RESULTS: Recommendations for the use of specific probiotic strains were made for the management of acute gastroenteritis, prevention of antibiotic-associated diarrhea, nosocomial diarrhea and necrotizing enterocolitis, management of Helicobacter pylori infection, and management of functional abdominal pain disorders and infant colic. CONCLUSIONS: Despite evidence to support the use of specific probiotics in some clinical situations, further studies confirming the effect(s) and defining the type, dose, and timing of probiotics are still often required. The use of probiotics with no documented health benefits should be discouraged.

Enteral Nutrition in Preterm Infants (2022): A Position Paper From the ESPGHAN Committee on Nutrition and Invited Experts.

OBJECTIVES: To review the current literature and develop consensus conclusions and recommendations on nutrient intakes and nutritional practice in preterm infants with birthweight <1800 g. METHODS: The European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee of Nutrition (CoN) led a process that included CoN members and invited experts. Invited experts with specific expertise were chosen to represent as broad a geographical spread as possible. A list of topics was developed, and individual leads were assigned to topics along with other members, who reviewed the current literature. A single face-to-face meeting was held in February 2020. Provisional conclusions and recommendations were developed between 2020 and 2021, and these were voted on electronically by all members of the working group between 2021 and 2022. Where >90% consensus was not achieved, online discussion meetings were held, along with further voting until agreement was reached. RESULTS: In general, there is a lack of strong evidence for most nutrients and topics. The summary paper is supported by additional supplementary digital content that provide a fuller explanation of the literature and relevant physiology: introduction and overview; human milk reference data; intakes of water, protein, energy, lipid, carbohydrate, electrolytes, minerals, trace elements, water soluble vitamins, and fat soluble vitamins; feeding mode including mineral enteral feeding, feed advancement, management of gastric residuals, gastric tube placement and bolus or continuous feeding; growth; breastmilk buccal colostrum, donor human milk, and risks of cytomegalovirus infection; hydrolyzed protein and osmolality; supplemental bionutrients; and use of breastmilk fortifier. CONCLUSIONS: We provide updated ESPGHAN CoN consensus-based conclusions and recommendations on nutrient intakes and nutritional management for preterm infants.

Association between duration of early empiric antibiotics and necrotizing enterocolitis and late-onset sepsis in preterm infants: a multicenter cohort study.

The threshold to initiate empiric antibiotics for suspicion of early-onset sepsis (EOS) is low in preterm infants. Antibiotics' effects on short-term outcomes have recently been debated. We aimed at exploring the extent of early empiric antibiotic exposure (EEAE) in preterm infants and the association between the duration of EEAE with necrotizing enterocolitis (NEC) and late-onset sepsis (LOS) within different EEAE groups. EEAE practice for suspicion of EOS was evaluated in all included infants (gestational age < 30 weeks) born in 9 centers in the Netherlands and Belgium between Oct. 2014 and Jan. 2019. EEAE association with NEC and LOS development was analyzed by multivariate regression. After excluding 56 EOS cases, 1259 infants were included. A total of 1122 infants (89.1%) were exposed to empirical antibiotics for the suspicion of EOS of whom 802 (63.7%) had short (≤ 72 h) and 320 (25.4%) prolonged EEAE (> 72 h). Infants with EEAE ≤ 72 h had a lower incidence of NEC compared to both infants without EEAE (adjusted odds ratio (aOR) 0.39; 95% confidence interval (CI) [0.19-0.80]; p = 0.01) and with prolonged EEAE (> 72 h) (aOR [95%CI]: 0.58 [0.35-0.96]; p = 0.03). With every additional day of EEAE, LOS incidence decreased (aOR [95%CI]: 0.90 [0.85-0.97]; p = 0.003). CONCLUSION: Almost 90% of preterm infants who have negative blood culture results in the first 72 h of life are exposed to EEAE under suspicion of EOS. One-fourth has prolonged EEAE. Duration of EEAE was differently associated with NEC and LOS incidence. The effects of antibiotics, and potentially induced microbial dysbiosis related to development of NEC and LOS, should further be explored. WHAT IS KNOWN: • Preterm infants often receive antibiotics empirically directly after birth for suspicion of early-onset sepsis. • The effects of the duration of early empirical antibiotic exposure on the risk for necrotizing enterocolitis and late-onset sepsis are debated. WHAT IS NEW: • Almost 90% of preterm infants with a gestational age below 30 weeks are exposed to antibiotics empirically after birth despite negative culture results. In a quarter of these culture-negative infants, empirical antibiotics are prolonged. • A short course of empirical antibiotics (≤72h) is associated with decreased odds for necrotizing enterocolitis compared to both prolonged (>72h) or no empirical antibiotics after birth. Furthermore, every additional day of empirical antibiotic exposure is associated with decreased risk for late-onset sepsis in the first month of life.

Endogenous Oxalate Production in Primary Hyperoxaluria Type 1 Patients.

BACKGROUND: Primary hyperoxaluria type 1 (PH1) is an inborn error of glyoxylate metabolism, characterized by increased endogenous oxalate production. The metabolic pathways underlying oxalate synthesis have not been fully elucidated, and upcoming therapies require more reliable outcome parameters than the currently used plasma oxalate levels and urinary oxalate excretion rates. We therefore developed a stable isotope infusion protocol to assess endogenous oxalate synthesis rate and the contribution of glycolate to both oxalate and glycine synthesis in vivo . METHODS: Eight healthy volunteers and eight patients with PH1 (stratified by pyridoxine responsiveness) underwent a combined primed continuous infusion of intravenous [1- 13 C]glycolate, [U- 13 C 2 ]oxalate, and, in a subgroup, [D 5 ]glycine. Isotopic enrichment of 13 C-labeled oxalate and glycolate were measured using a new gas chromatography-tandem mass spectrometry (GC-MS/MS) method. Stable isotope dilution and incorporation calculations quantified rates of appearance and synthetic rates, respectively. RESULTS: Total daily oxalate rates of appearance (mean [SD]) were 2.71 (0.54), 1.46 (0.23), and 0.79 (0.15) mmol/d in patients who were pyridoxine unresponsive, patients who were pyridoxine responsive, and controls, respectively ( P =0.002). Mean (SD) contribution of glycolate to oxalate production was 47.3% (12.8) in patients and 1.3% (0.7) in controls. Using the incorporation of [1- 13 C]glycolate tracer in glycine revealed significant conversion of glycolate into glycine in pyridoxine responsive, but not in patients with PH1 who were pyridoxine unresponsive. CONCLUSIONS: This stable isotope infusion protocol could evaluate efficacy of new therapies, investigate pyridoxine responsiveness, and serve as a tool to further explore glyoxylate metabolism in humans.

Insulin Concentration in Human Milk in the First Ten Days Postpartum: Course and Associated Factors.

BACKGROUND OBJECTIVES: Human milk (HM) is better tolerated than formula in preterm infants. Insulin, which is naturally present in HM but not in formula, has been suggested as a key factor for feeding tolerance, as it appears to stimulate intestinal maturation. Its precise concentrations during the early postnatal period, however, remains unknown. The objective of this study was to assess the natural timecourse of the HM insulin concentration during the first ten days postpartum. The effect of preterm delivery, maternal obesity, and diurnal rhythm were also assessed. METHOD: HM was collected from 31 non-diabetic mothers (21 preterm [gestational age (GA) < 37 weeks]; 10 at-term [GA ≥ 37 weeks]) on ≥ 4 time-points per day during the first five days, and once on the tenth day postpartum. RESULTS: The HM insulin concentration declined rapidly within the first three days postpartum (day 1: 516 [312-1058] pmol/L; day 3: 157 [87-299] pmol/L), after which the concentration remained relatively stable. The insulin concentrations were higher in HM from obese mothers than from non-obese mothers (P < 0.001). Preterm delivery did not significantly affect HM insulin concentrations when adjusted for maternal pre-pregnancy body mass index category (P = 0.270). Diurnal rhythm was characterized by an insulin concentration decline throughout the night (P = 0.001), followed by an increase in the morning (P = 0.001). CONCLUSION: The HM insulin concentration declines rapidly in the first three days postpartum, follows a diurnal rhythm, and is higher in obese mothers compared to non-obese mothers. HM insulin concentrations are not affected by preterm delivery.

Probiotics and Preterm Infants: A Position Paper by the European Society for Paediatric Gastroenterology Hepatology and Nutrition Committee on Nutrition and the European Society for Paediatric Gastroenterology Hepatology and Nutrition Working Group for Probiotics and Prebiotics.

More than 10,000 preterm infants have participated in randomised controlled trials on probiotics worldwide, suggesting that probiotics in general could reduce rates of necrotising enterocolitis (NEC), sepsis, and mortality. Answers to relevant clinical questions as to which strain to use, at what dosage, and how long to supplement are, however, not available. On the other hand, an increasing number of commercial products containing probiotics are available from sometimes suboptimal quality. Also, a large number of units around the world are routinely offering probiotic supplementation as the standard of care despite lacking solid evidence. Our recent network meta-analysis identified probiotic strains with greatest efficacy regarding relevant clinical outcomes for preterm neonates. Efficacy in reducing mortality and morbidity was found for only a minority of the studied strains or combinations. In the present position paper, we aim to provide advice, which specific strains might potentially be used and which strains should not be used. In addition, we aim to address safety issues of probiotic supplementation to preterm infants, who have reduced immunological capacities and occasional indwelling catheters. For example, quality reassurance of the probiotic product is essential, probiotic strains should be devoid of transferable antibiotic resistance genes, and local microbiologists should be able to routinely detect probiotic sepsis. Provided all safety issues are met, there is currently a conditional recommendation (with low certainty of evidence) to provide either Lactobacillus rhamnosus GG ATCC53103 or the combination of Bifidobacterium infantis Bb-02, Bifidobacterium lactis Bb-12, and Streptococcus thermophilus TH-4 in order to reduce NEC rates.

Nutrient Fortification of Human Donor Milk Affects Intestinal Function and Protein Metabolism in Preterm Pigs.

Background: Nutrient fortification of human milk is often required to secure adequate growth and organ development for very preterm infants. There is concern that formula-based fortifiers (FFs) induce intestinal dysfunction, feeding intolerance, and necrotizing enterocolitis (NEC). Bovine colostrum (BC) may be an alternative nutrient fortifier, considering its high content of protein and milk bioactive factors. Objective: We investigated whether BC was superior to an FF product based on processed bovine milk and vegetable oil to fortify donor human milk (DHM) for preterm pigs, used as a model for infants. Methods: Sixty preterm pigs from 4 sows (Danish Landrace × Large White × Duroc, birth weight 944 ± 29 g) received decreasing volumes of parenteral nutrition (96-72 mL â‹… kg-1 â‹… d-1) and increasing volumes of enteral nutrition (24-132 mL â‹… kg-1 â‹… d-1) for 8 d. Pigs were fed donor porcine milk (DPM) and DHM with or without FF or BC fortification (+4.6 g protein â‹… kg-1 â‹… d-1). Results: DPM-fed pigs showed higher growth (10-fold), protein synthesis (+15-30%), villus heights, lactase and peptidase activities (+30%), and reduced intestinal cytokines (-50%) relative to DHM pigs (all P < 0.05). Fortification increased protein synthesis (+20-30%), but with higher weight gain and lower urea and cortisol concentrations for DHM+BC compared with DHM+FF pigs (2- to 3-fold differences, all P ≤ 0.06). DHM+FF pigs showed more diarrhea and reduced lactase and peptidase activities, hexose uptake, and villus heights relative to DHM+BC or DHM pigs (30-90% differences, P < 0.05). Fortification did not affect NEC incidence but DHM+BC pigs had lower colonic interleukin (IL)-6 and IL-8 concentrations relative to the remaining pigs (-30%, P = 0.06). DHM+FF pigs had higher stomach bacterial load than did DHM, and higher bacterial density along intestinal villi than did DHM and DHM+BC pigs (2- to 3-fold, P < 0.05). Conclusions: The FF product investigated in this study reduced growth, intestinal function, and protein utilization in DHM-fed preterm pigs, relative to BC as fortifier. The relevance of BC as an alternative nutrient fortifier for preterm infants should be tested.

Probiotics for Preterm Infants: A Strain-Specific Systematic Review and Network Meta-analysis.

OBJECTIVES: Several randomized controlled trials (RCTs) on the use of probiotics to reduce morbidity and mortality in preterm infants have provided inconsistent results. Although meta-analyses that group all of the used strains together are suggesting efficacy, it is not possible to determine the most effective strain that is more relevant to the clinician. We therefore used a network meta-analysis (NMA) approach to identify strains with greatest efficacy. METHODS: A PubMed search identified placebo-controlled or head-to-head RCTs investigating probiotics in preterm infants. From trials that recorded mortality, necrotizing enterocolitis, late-onset sepsis, or time until full enteral feeding as outcomes, data were extracted and Bayesian hierarchical random-effects models were run to construct a NMA. RESULTS: Fifty-one RCTs involving 11,231 preterm infants were included. Most strains or combinations of strains were only studied in one or a few RCTs. Only 3 of 25 studied probiotic treatment combinations showed significant reduction in mortality rates. Seven treatments reduced necrotizing enterocolitis incidence, 2 reduced late-onset sepsis, and 3 reduced time until full enteral feeding. There was no clear overlap of strains, which were effective on multiple outcome domains. CONCLUSIONS: This NMA showed efficacy in reducing mortality and morbidity only in a minority of the studied strains or combinations. This may be due to an inadequate number, or size, of RCTs, or due to a true lack of effect for certain species. Further large and adequately powered RCTs using strains with the greatest apparent efficacy will be needed to more precisely define optimal treatment strategies.

Observational outcome results following a randomized controlled trial of early amino acid administration in preterm infants.

OBJECTIVE: Several reports have investigated amino acid administration in premature infants during the early postnatal phase. Most of these previous studies, however, have only evaluated short-term in-hospital outcomes. Our aim was to describe long-term outcomes in premature infants previously subjected to different nutritional regimens in a randomized controlled trial. The primary outcome was survival without major disabilities, and the secondary outcomes included anthropometry and mental development. METHODS: Infants born <32 weeks' gestation and <1500 g were randomized to receive glucose (n = 69) or glucose with 2.4 g · kg(-1) · day(-1 amino acids) (n = 63) from birth. From postnatal day 3 onward, the nutritional intake was similar. At 2 years of corrected age, the surviving infants were assessed for neurodevelopmental outcome and anthropometry. RESULTS: Ninety-seven percent of the surviving infants were examined at follow-up, with no overall effect on survival without major disabilities. Boys, however, had a normal outcome significantly more often if amino acids were administered from birth onward (crude odds ratio 3.8, 95% confidence interval 1.3-11.4) and following adjustment for confounders (odds ratio 6.2, 95% confidence interval 1.0-38.0). The secondary outcomes exhibited no differences in anthropometric data. The mental developmental index was lower in the small number of girls who survived without major disabilities following the early administration of amino acids. CONCLUSIONS: In this hypothesis-generating outcome study, premature boys, but not girls, benefited from amino acid administration directly following birth. The observed lower mental developmental index in a subgroup of girls, however, warrants further studies.

Growth and fatty acid profiles of VLBW infants receiving a multicomponent lipid emulsion from birth.

OBJECTIVES: Very-low-birth-weight (VLBW) infants are dependent on parenteral nutrition after birth. A parenteral lipid emulsion with a multicomponent composition may improve growth and neurodevelopment and may prevent liver injury, which is often observed in association with long-term parenteral nutrition with pure soybean oil. Our aim was to evaluate the safety and efficacy of a multicomponent lipid emulsion containing 30% soybean oil, 30% medium-chain triacylglycerol, 25% olive oil, and 15% fish oil compared with a conventional pure soybean oil emulsion in VLBW infants. METHODS: We conducted a double-blind randomized controlled trial in VLBW infants randomized to parenteral nutrition with the multicomponent (study group) or pure soybean oil emulsion (control group) from birth at a dose of 2 to 3 g · kg(-1) · day(-1) until the infants were receiving full enteral nutrition. We assessed efficacy by growth rates and measuring plasma fatty acid profiles (representative subset). Safety was evaluated by assessing hematologic and biochemical parameters, potentially harmful phytosterol concentrations (same subset), and clinical neonatal outcome parameters. RESULTS: Ninety-six infants were included (subsets n = 21). The multicomponent emulsion was associated with higher weight and head circumference z scores during admission. Plasma eicosapentaenoic acid and docosahexaenoic acid concentrations were higher in the study group. The hematological, biochemical, and neonatal outcomes were not different between groups, whereas the plasma concentrations of phytosterols were higher in the control group. CONCLUSIONS: The multicomponent lipid emulsion was well tolerated and associated with improved growth and higher plasma fatty acid profiles in VLBW infants in comparison with the pure soybean oil emulsion.

Safe and efficient practice of parenteral nutrition in neonates and children aged 0-18 years - The role of licensed multi-chamber bags.

Parenteral nutrition (PN) is recognized as a complex high-risk therapy. Its practice is highly variable and frequently suboptimal in pediatric patients. Optimizing care requires evidence, consensus-based guidelines, audits of practice, and standardized strategies. Several pediatric scientific organizations, expert panels, and authorities have recently recommended that standardized PN should generally be used over individualized PN in the majority of pediatric patients including very low birth weight premature infants. In addition, PN admixtures produced and validated by a suitably qualified institution are recommended over locally produced PN. Licensed multi chamber bags are standardized PN bags that comply with Good Manufacturing Practice and high-quality standards for the finished product in the frame of their full manufacturing license. The purpose of this article is to review the practical aspects of PN and the evidence for using such multi-chamber bags in pediatric patients. It highlights the safety characteristics and the limitations of the different PN practices and provides some guidance for ensuring safe and efficient therapy in pediatric patients.

Identifying Preoperative Clinical Characteristics of Unexpected Gastrointestinal Perforation in Infants-A Retrospective Cohort Study.

BACKGROUND: Infants presenting with unexpected pneumoperitoneum upon abdominal X-ray, indicating a gastrointestinal perforation (GIP), have a surgical emergency with potential morbidity and mortality. Preoperative determination of the location of perforation is challenging but will aid the surgeon in optimizing the surgical strategy, as colon perforations are more challenging than small bowel perforations. Therefore, the aim of this study is to provide an overview of preoperative patient characteristics, determine the differences between the small bowel and colon, and determine underlying causes in a cohort of infants with unexpected GIP. METHODS: All infants (age ≤ 6 months) who presented at our center with unexpected pneumoperitoneum (no signs of pneumatosis before) undergoing surgery between 1996 and 2024 were retrospectively included. The differences between the location of perforation were analyzed using chi-squared and t-tests. Bonferroni correction was used to adjust for multiple tests. RESULTS: In total, 51 infants presented with unexpected pneumoperitoneum at our center, predominantly male (N = 36/51) and premature (N = 40/51). Among them, twenty-six had small bowel, twenty-two colon, and three stomach perforations. Prematurity (p = 0.001), birthweight < 1000 g (p = 0.001), respiratory support (p = 0.001), and lower median arterial pH levels (p = 0.001) were more present in patients with small bowel perforation compared with colon perforations. Pneumatosis intestinalis was more present in patients with colon perforation (p = 0.004). All patients with Hirschsprung disease and cystic fibrosis had colon perforation. The final diagnoses were mainly focal intestinal perforations (N = 27/51) and necrotizing enterocolitis (N = 9/51). CONCLUSIONS: Infants with unexpected GIP, birthweight < 1000 g, and prematurity have more risk for small bowel perforation. In case of colon perforation, additional screening (for Hirschsprung and cystic fibrosis) should be considered.

Safety and efficacy of early parenteral lipid and high-dose amino acid administration to very low birth weight infants.

OBJECTIVE: To assess the efficacy and safety of early parenteral lipid and high-dose amino acid (AA) administration from birth onwards in very low birth weight (VLBW, birth weight <1500 g) infants. STUDY DESIGN: VLBW infants (n = 144; birth weight 862 ± 218 g; gestational age 27.4 ± 2.2 weeks) were randomized to receive 2.4 g of AA kg(-1) · d(-1) (control group), or 2.4 g AA kg(-1) · d(-1) plus 2-3 g lipids kg(-1) · d(-1) (AA + lipid group), or 3.6 g AA kg(-1) · d(-1) plus 2-3 g lipids kg(-1) · d(-1) (high AA + lipid group) from birth onwards. The primary outcome was nitrogen balance. The secondary outcomes were biochemical variables, urea rate of appearance, growth rates, and clinical outcome. RESULTS: The nitrogen balance on day 2 was significantly greater in both intervention groups compared with the control group. Greater amounts of AA administration did not further improve nitrogen balance compared with standard AA dose plus lipids and was associated with high plasma urea concentrations and high rates of urea appearance. No differences in other biochemical variables, growth, or clinical outcomes were observed. CONCLUSIONS: In VLBW infants, the administration of parenteral AA combined with lipids from birth onwards improved conditions for anabolism and growth, as shown by improved nitrogen balance. Greater levels of AA administration did not further improve the nitrogen balance but led to increased AA oxidation. Early lipid initiation and high-dose AA were well tolerated.

High-precision mass spectrometric analysis using stable isotopes in studies of children.

The use of stable isotopes combined with mass spectrometry (MS) provides insight into metabolic processes within the body. Herein, an overview on the relevance of stable isotope methodology in pediatric research is presented. Applications for the use of stable isotopes with MS cover carbohydrate, fat, and amino acid metabolism as well as body composition, energy expenditure, and the synthesis of specific peptides and proteins, such as glutathione and albumin. The main focus of these studies is on the interactions between nutrients and the endogenous metabolism within the body and how these factors affect the health of a growing infant. Considering that the early imprinting of metabolic processes hugely impacts metabolism (and thus functional outcome) later in life, research in this area is important and is advancing rapidly. The major fluxes on a metabolic level are the synthesis and breakdown rates. They can be quantified using kinetic tracer analysis and mathematical modeling. Organic MS and isotope ratio mass spectrometry (IRMS) are the two most mature techniques for the isotopic analysis of compounds. Introduction of the samples is usually done by coupling gas chromatography (GC) to either IRMS or MS because it is the most robust technique for specific isotopic analysis of volatile compounds. In addition, liquid chromatography (LC) is now being used more often as a tool for sample introduction of both volatile and non-volatile compounds into IRMS or MS for (13)C isotopic analyses at natural abundances and for (13)C-labeled enriched compounds. The availability of samples is often limited in pediatric patients. Therefore, sample size restriction is important when developing new methods. Also, the availability of stable isotope-labeled substrates is necessary for measurements of the kinetics and concentrations in metabolic studies, which can be a limiting factor. During the last decade, the availability of these substrates has increased. Furthermore, improvements in the accuracy, precision, and sensitivity of existing techniques (such as GC/IRMS) and the development of new techniques (such as LC/IRMS) have opened up new avenues for tackling these limitations.