Neonatal hypoglycemia--answers, but more questions

The Term Newborn: Hypoglycemia

This review provides an update on neonatal hypoglycemia in the term infant, including discussion of glucose metabolism, definitions of hypoglycemia, identification of infants commonly at risk, and the screening, treatment, and potential neurologic outcomes of postnatal hypoglycemia. Neonatal hypoglycemia is a common metabolic condition that continues to plague clinicians because there is no clear relationship between low glucose concentrations or their duration that determines adverse neurologic outcomes. However, severely low, prolonged, recurrent low glucose concentrations in infants who also have marked symptoms such as seizures, flaccid hypotonia with apnea, and coma clearly are associated with permanent brain damage. Early identification of at-risk infants, early and continued breastfeeding augmented with oral dextrose gel, monitoring prefeed glucose concentrations, treating symptomatic infants who have very low and recurrent low glucose concentrations, and identifying and aggressively managing infants with persistent hyperinsulinemia and metabolic defects may help prevent neuronal injury.

[Prospective study on influence of perinatal factors on the development of early neonatal hypoglycemia in late-preterm and term infants]

INTRODUCTION AND OBJECTIVE

Neonatal hypoglycemia offers multiple controversies. The study aims to assess the main factors involved in the development of early hypoglycemia in term and late preterm infants, and the implication of different environmental circumstances.

METHODS

A prospective cohort study, in infants born between 34 0/7 weeks and 36 6/7 weeks of gestation. Three capillary blood glucose determinations were performed during the eight first hours after birth.

SAMPLE SIZE

207; 59 neonates developed hypoglycemia.

RESULTS

Prenatal risk factors include gestational diabetes with poor glycemic control, twin pregnancy and gestational age. The presence of meconium amniotic fluid and planned cesarean delivery are associated with a higher probability of hypoglycemia. After birth, skin to skin contact, breastfeeding, soft lightening, and normothermia are described as protective factors. The predictive model that combines the type of lightening, body temperature and the excess of bases level, correctly classifies 98% of the severe hypoglycemia cases, with a high Nagelkerke R2 value (0.645) and specificity of 99.5%.

CONCLUSIONS

Postnatal environmental factors seem to be directly related to early hypoglycemia development, so it is essential to support the maternal-child union and breastfeeding. Our results allow better identification of neonates who are not subsidiary to performing blood glucose determinations because they have little risk of developing it.

Glucose Profiles in Healthy Term Infants in the First 5 Days: The Glucose in Well Babies (GLOW) Study

OBJECTIVES

To determine postnatal changes in plasma and interstitial glucose concentrations of healthy infants receiving current recommended care and to compare the incidence of low concentrations with recommended thresholds for treatment of at-risk infants.

STUDY DESIGN

A prospective masked observational study in Hamilton, New Zealand. Healthy, term, appropriately grown singletons had continuous glucose monitoring and repeated heel-prick plasma glucose measurements (4 in the first 24 hours then twice daily using the glucose oxidase method) from birth to 120 hours.

RESULTS

The 67 infants had a mean birth weight of 3584 ± 349 g, and gestational age of 40.1 ± 1.2 weeks. The mean glucose concentrations increased over the first 18 hours, remained stable to 48 hours (59 ± 11 mg/dL; 3.3 ± 0.6 mmol/L)] before increasing to a new plateau by the fourth day (89 ± 13 mg/dL; 4.6 ± 0.7 mmol/L). Plasma glucose concentrations of 47 mg/dL (2.6 mmol/L) approximated the 10th percentile in the first 48 hours, and 39% of infants had ≥1 episode below this threshold. Early term infants had lower mean glucose concentrations than those born at later gestational ages and were more likely to have episodes <47 mg/dL (<2.6 mmol/L) (19/32 [59%] vs 7/35 [20%]; relative risk, 3.0; 95% CI, 1.4-6.1; P = .001).

CONCLUSIONS

Healthy infants seem to complete their metabolic transition by day 4. Many have glucose concentrations below the accepted thresholds for treatment of hypoglycemia.

TRIAL REGISTRATION

ACTRN: 12615000986572.

Neonatal hypoglycemia and the CPT1A P479L variant in term newborns: A retrospective cohort study of Inuit newborns from Kivalliq Nunavut

Introduction

Neonatal hypoglycemia (NH) in the first days of life can largely be prevented by recognizing those at risk and managing accordingly. The CPT1A P479L variant is prevalent in northern Indigenous populations and is a possible risk factor for hypoglycemia. We report on NH incidence in the Kivalliq region of Nunavut, where all Inuit newborns are screened for NH.

Methods

We reviewed clinical charts of 728 Inuit newborns from Kivalliq (January 1, 2010 to December 31, 2013) for blood glucose (BG) levels and infant/maternal characteristics, linking to CPT1A genotype; 616 newborns had BG data from 2 to 48 hours of life. NH was defined using Canadian Paediatric Society guidelines (≤2.0 mmol/L at 2 hours, <2.6 mmol/L at 2 to 48 hours).

Results

NH was documented in 21.4% overall, 24.4% of at-risk newborns and 19.5% of term newborns with no risk factors (≥37 weeks gestation, term-NRF). NH was documented in 22.0% of CPT1A P479L homozygous, 19.8% of P479L heterozygous and 4.8% of noncarrier term-NRF newborns. With multivariable logistic regression, the adjusted ORs for developing NH in term-NRF newborns was 4.97 for CPT1A P479L homozygotes (95% confidence interval [CI]:0.65-38.35, P=0.19) and 4.71 for P479L heterozygotes (95% CI:0.57-37.89, P=0.15).

Conclusion

Term-NRF newborns had a higher NH incidence than previously reported, similar to that for at-risk newborns, possibly due to the CPT1A P479L variant. Since only Inuit newborns from Kivalliq are screened for NH, further study of long-term outcomes of NH in this population and the role of the P479L variant are warranted to determine if neonatal BG screening is indicated in all Inuit newborns.

Does umbilical cord blood glucose extraction discriminate the risk of early neonatal hypoglycaemia in at-risk newborns?

AIM

Despite targeting newborns at risk of hypoglycaemia based on clinical characteristics, blood glucose measured at 1 and 4 h of age is frequently normal. Identification of at-risk newborns at the greatest risk of hypoglycaemia would allow more targeted, earlier intervention. We aimed to determine the ability of calculated umbilical cord blood glucose extraction to discriminate hypoglycaemia in at-risk newborns in the first 4 h of life.

METHODS

Newborns with paired arterial and venous cord blood glucose and 1 ± 4 h capillary or venous blood glucose measured using a blood gas analyser (radiometer) were retrospectively identified (n = 154). Hypoglycaemia was defined as a blood glucose ≤2.0 mmol/L. The ability of calculated umbilical cord blood glucose extraction to discriminate risk of hypoglycaemia was determined by an receiver operating characteristic (ROC) curve.

RESULTS

Twenty-seven newborns (18%) had a blood glucose ≤2.0 mmol/L at either time point. Neither arterial nor venous cord blood glucose predicted early hypoglycaemia better than chance. The area under the ROC curve for umbilical cord blood glucose extraction (area under the ROC curve = 0.74, (95% confidence interval, 0.65-0.82)) was significantly better than chance and arterial or venous cord blood glucose. An umbilical cord blood glucose extraction of 16% had the best sensitivity (80%) and specificity (55%) for discriminating the risk of early hypoglycaemia.

CONCLUSIONS

Umbilical cord blood glucose extraction discriminates the risk of early hypoglycaemia at 1 or 4 h of age. However, the clinical utility of this test is limited due to the low sensitivity and specificity. Its predictive value may be greater in specific subsets of at-risk newborns and warrants further investigation.

Glucose Gel as a Potential Alternative Treatment to Infant Formula for Neonatal Hypoglycaemia in Australia

Infant formula is often used as a treatment for neonatal hypoglycaemia in Australia; however, there are concerns that this may jeopardise mother-baby bonding and breastfeeding. Successful use of glucose gel as an alternative treatment for hypoglycaemia has been reported. We wanted to investigate in a pilot study whether the use of glucose gel has the potential to quickly and safely restore normoglycaemia in the infants of diabetic mothers in an Australian setting. Infants with asymptomatic hypoglycaemia were treated with glucose gel (n = 36) and compared to a historical group of infants which had been treated with infant formula (n = 24). Within 15 min of the first treatment, the gel group had a mean blood glucose level (BGL) of 2.6 mmol/L, and 2.7 mmol/L 30 min after the second treatment. This was lower than the BGL after the first treatment for the formula group, which rose to a mean of 2.8 then to 3.2 mmol/L after the second treatment (p = 0.003). In successfully treated infants, administration of the gel resulted in normoglycaemia within 30 min. The likelihood of special care nursery admission was not significantly different between the groups, although we had a small sample size, and our findings should be interpreted with caution. These pilot results provide support for further investigations into the use of glucose gel as an alternative treatment to infant formula.

A Quality-Improvement Initiative to Reduce NICU Transfers for Neonates at Risk for Hypoglycemia

BACKGROUND AND OBJECTIVE

Neonatal hypoglycemia is a common problem, often requiring management in the NICU. Nonpharmacologic interventions, including early breastfeeding and skin-to-skin care (SSC), may prevent hypoglycemia and the need to escalate care. Our objective was to maintain mother-infant dyads in the mother-infant unit by decreasing hypoglycemia resulting in NICU transfer.

METHODS

Inborn infants ≥35 weeks' gestation with at least 1 risk factor for hypoglycemia were included. Using quality-improvement methodology, a bundle for at-risk infants was implemented, which included a protocol change focusing on early SSC, early feeding, and obtaining a blood glucose measurement in asymptomatic infants at 90 minutes. The primary outcome was the overall transfer rate of at-risk infants to the NICU. Secondary outcomes were related to protocol adherence. Balancing measures, including the rate of symptomatic hypoglycemia and sepsis evaluations, were monitored. Statistical process control charts using standard interpretation rules were used to monitor for improvement in key aims.

RESULTS

For infants at risk for hypoglycemia, the NICU transfer rate decreased from 17% to 3% overall. Documented early feeding and SSC in at-risk newborns increased. The percent of at-risk infants transferred to the NICU who did not require intravenous dextrose decreased from 5% at baseline to 0.7% after intervention. There were no adverse outcomes observed in the period before or after the intervention.

CONCLUSIONS

The implementation of a quality-improvement intervention promoting SSC and early feeding in at-risk infants was associated with a decreased rate of transfer to the NICU for hypoglycemia.

Neonatal hypoglycemia

A consistent definition for neonatal hypoglycemia in the first 48 h of life continues to elude us. Enhanced understanding of metabolic disturbances and genetic disorders that underlie alterations in postnatal glucose homeostasis has added useful information to understanding transitional hypoglycemia. This growth in knowledge still has not led to what we need to know: "How low is too low and for how long?" This article reviews the current state of understanding of neonatal hypoglycemia and how different approaches reach different "expert" opinions.

Developmental Outcomes of Preterm Infants With Neonatal Hypoglycemia

BACKGROUND AND OBJECTIVES

Neonatal hypoglycemia has been associated with abnormalities on brain imaging and a spectrum of developmental delays, although historical and recent studies show conflicting results. We compared the cognitive, academic, and behavioral outcomes of preterm infants with neonatal hypoglycemia with those of normoglycemic controls at 3 to 18 years of age.

METHODS

A secondary analysis of data from the Infant Health and Development Program, a national, multisite, randomized controlled longitudinal intervention study of long-term health and developmental outcomes in preterm infants. Of the 985 infants enrolled in the Infant Health and Development Program, 745 infants had glucose levels recorded. Infants were stratified into 4 groups by glucose level. By using standardized cognitive, academic, and behavioral assessments performed at 3, 8, and 18 years of age, we compared groups after adjusting for intervention status, birth weight, gestational age, sex, severity of neonatal course, race, maternal education, and maternal preconception weight.

RESULTS

No significant differences were observed in cognitive or academic skills between the control and effected groups at any age. Participants with more severe neonatal hypoglycemia reported fewer problem behaviors at age 18 than those without hypoglycemia.

CONCLUSIONS

No significant differences in intellectual or academic achievement were found between preterm infants with and without hypoglycemia. A statistical difference was found in behavior at age 18, with hypoglycemic children showing fewer problematic behaviors than normoglycemic children. This difference was not clinically meaningful. Using extended outcomes, our results are consistent with previous studies that found no significant neurodevelopmental outcomes associated with neonatal hypoglycemia in preterm-born children.

Defining the Phenotype and Assessing Severity in Phosphoglucomutase-1 Deficiency

OBJECTIVE

To define phenotypic groups and identify predictors of disease severity in patients with phosphoglucomutase-1 deficiency (PGM1-CDG).

STUDY DESIGN

We evaluated 27 patients with PGM1-CDG who were divided into 3 phenotypic groups, and group assignment was validated by a scoring system, the Tulane PGM1-CDG Rating Scale (TPCRS). This scale evaluates measurable clinical features of PGM1-CDG. We examined the relationship between genotype, enzyme activity, and TPCRS score by using regression analysis. Associations between the most common clinical features and disease severity were evaluated by principal component analysis.

RESULTS

We found a statistically significant stratification of the TPCRS scores among the phenotypic groups (P < .001). Regression analysis showed that there is no significant correlation between genotype, enzyme activity, and TPCRS score. Principal component analysis identified 5 variables that contributed to 54% variance in the cohort and are predictive of disease severity: congenital malformation, cardiac involvement, endocrine deficiency, myopathy, and growth.

CONCLUSIONS

We established a scoring algorithm to reliably evaluate disease severity in patients with PGM1-CDG on the basis of their clinical history and presentation. We also identified 5 clinical features that are predictors of disease severity; 2 of these features can be evaluated by physical examination, without the need for specific diagnostic testing and thus allow for rapid assessment and initiation of therapy.

New approaches to management of neonatal hypoglycemia

Despite being a very common problem after birth, consensus on how to manage low glucose concentrations in the first 48 h of life has been difficult to establish and remains a debated issue. One of the reasons for this is that few studies have provided the type of data needed to establish a definitive approach agreed upon by all. However, some recent publications have provided much needed primary data to inform this debate. These publications have focused on aspects of managing low blood glucose concentrations in the patients most at-risk for asymptomatic hypoglycemia—those born late-preterm, large for gestational age, small for gestational age, or growth restricted, and those born following a pregnancy complicated by diabetes mellitus. The goal of this review is to discuss specific aspects of this new research. First, we focus on promising new data testing the role of buccal dextrose gel in the management of asymptomatic neonatal hypoglycemia. Second, we highlight some of the clinical implications of a large, prospective study documenting the association of specific glycemic patterns with neurodevelopmental outcomes at two years of age.

Neonatal hypoglycemia

PURPOSE OF REVIEW

The screening and management for neonatal hypoglycemia remains a confusing and contentious problem in neonatology. The purpose of this article is to contrast recent recommendations from the American Academy of Pediatrics and the Pediatric Endocrine Society.

RECENT FINDINGS

Using different methodologies, the organizations have significant differences on whom to screen and what levels of glucose should be used for management. The identification of the first 48 h as a transitional hyperinsulinemic state is a new important concept. The neuroendocrine approach is contrasted with a neurodevelopmental strategy to find levels that exceed those associated with neuroglycopenia.

SUMMARY

The questions remain the same when it comes to screening and management of neonatal low-glucose levels. Recent outcome studies with differing results continue to add to the controversy as to what to do at the bedside. It is uncertain if universal screening of glucose levels in the first hours should be applied to all newborn infants. Persistent hypoglycemic syndromes must be identified prior to discharge.

Metabolic screening and postnatal glucose homeostasis in the newborn

Although individual metabolic diseases are relatively uncommon, inherited metabolic diseases collectively represent a more common cause of disease in the neonatal period than is generally appreciated. Newborn screening is among the most successful public health programs today. Every day, newborns considered to be at risk for hypoglycemia are screened. The definition of clinically significant hypoglycemia remains among the most confused and contentious issues in neonatology. There are 2 "competing" methods of defining hypoglycemia that suggest very different levels for management: one based on metabolic-endocrinologic hormones and another that uses outcome data to determine threshold levels of risk.

Pediatric hypoglycemia

Hypoglycemia in the pediatric population is a common finding important to recognize and manage to prevent brain injury. Recent advances in molecular genetics have provided new insight into its biochemical and physiologic basis and have led to more appropriate and specific treatment. Although a major cause of brain injury in pediatrics, the ability to predict the long-term outcome in these patients remains difficult. Identification of these at-risk individuals is important. The physiologic adaptations associated with transition from fetal to neonatal life are now better understood thus allowing for improved surveillance and management. Despite these advances, analytical limitations of point-of-care testing instruments at low glucose concentration continue to persist, This review aims to address these questions and provide an overview of pediatric hypoglycemia and the molecular pathways involved.

Neonatal endocrine emergencies: a primer for the emergency physician

The resuscitation principles of securing the airway and stabilizing hemodynamics remain the same in any neonatal emergency. However, stabilizing endocrine disorders may prove especially challenging. Several organ systems are affected simultaneously and the clinical presentation can be subtle. Although not all-inclusive, the implementation of newborn screening tests has significantly reduced morbidity and mortality in neonates. Implementing routine screening tests worldwide and improving the accuracy of present tests remains the challenge for healthcare providers. With further study of these disorders and best treatment practices we can provide neonates presenting to the emergency department with the best possible outcomes.

Hypoglycemia in Prader-Willi syndrome

Although mouse models of Prader-Willi syndrome (PWS) suggest that hypoglycemia may be part of this syndrome, review of the literature shows little evidence that it is an issue in humans with PWS. Both adrenal and growth hormone deficiency can be seen in PWS, and both of these hormone deficiencies are associated with increased risk for hypoglycemia. We reviewed medical records for patients with PWS seen at the University of Florida Prader-Willi Program. Children were 2 months to 5 years of age. We recorded the presence, degree, and persistence of hypoglycemia, age of first occurrence, genetic diagnosis, and gestational age. Repeated hypoglycemia was determined if individuals had multiple blood glucose (BG) values <50 mg/dl before 1 month old, or BG levels <50 mg/dl once and additional BG values <70 mg/dl after 1 year of age. Of 95 patient charts reviewed, 12 (12.6%) had recorded hypoglycemia. Six of 12 patients with hypoglycemia had documented BG levels <40 mg/dl. Seven had their first episode of hypoglycemia within the first day of life. Of these seven individuals, five had BG <40 mg/dl. Repeated hypoglycemia was noted in 10 patients (83% of all patients with hypoglycemia). Only two with hypoglycemia had documented adrenal insufficiency. Our study suggests that infants with PWS may be predisposed to hypoglycemia from birth. Additional investigation is necessary to confirm our findings and define the cause of hypoglycemia. If the presence of hypoglycemia is confirmed, early detection and treatment may result in improved neurocognitive outcomes.

Audit of a clinical guideline for neonatal hypoglycaemia screening

AIM

This study aims to evaluate adherence to a clinical guideline for screening and prevention of neonatal hypoglycaemia on the post-natal wards.

METHODS

Retrospective chart review of 581 healthy term neonates born at a tertiary maternity hospital. Indications for hypoglycaemia screening included small for gestational age (SGA), infants of diabetic mothers (IDM; gestational, Type 1 or 2), symptomatic hypoglycaemia, macrosomia and wasted (undernourished) appearance. Outcomes were protocol entry and adherence with hypoglycaemia prevention strategies including early and frequent feeding and timely blood glucose measurement.

RESULTS

Of 115 neonates screened for hypoglycaemia, 67 were IDM, 19 were SGA (including two both IDM and SGA), and two were macrosomic. One IDM and one SGA were not screened. Twenty-two neonates were screened for a reason not identifiable from the medical record, and 13 neonates were SGA by a definition different to the guideline definition, including five who were also IDM. Guideline adherence was variable. Few neonates (41 of 106, 39%) were fed in the first post-natal hour, and blood glucose measurement occurred later than recommended for 41 of 106 (39%) of neonates.

CONCLUSIONS

Most IDM and SGA neonates were screened. While guideline adherence overall was comparable with other studies, neonates were fed late. We recommend staff education about benefits of early (within the first hour) frequent breastfeeding for neonates at risk.