Outcomes among newborns with total serum bilirubin levels of 25 mg per deciliter or more

Transcutaneous bilirubinometry for detecting jaundice in term or late preterm neonates

BACKGROUND

The American Academy of Pediatrics and the Canadian Paediatric Society both advise that all newborns should undergo bilirubin screening before leaving the hospital, and this has become the standard practice in both countries. However, the US Preventive Task Force has found no strong evidence to suggest that this practice of universal screening for bilirubin reduces the occurrence of significant outcomes such as bilirubin-induced neurologic dysfunction or kernicterus.

OBJECTIVES

To evaluate the effectiveness of transcutaneous screening compared to visual inspection for hyperbilirubinemia to prevent the readmission of newborns (infants greater than 35 weeks' gestation) for phototherapy.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, ICTRP, and ISRCTN in June 2023. We also searched conference proceedings, and the reference lists of included studies.

SELECTION CRITERIA

We included randomized controlled trials (RCTs), quasi-randomized, cluster-randomized, or prospective cohort studies with control arm that evaluated the use of transcutaneous bilirubin (TcB) screening for hyperbilirubinemia in newborns before hospital discharge.

DATA COLLECTION AND ANALYSIS

We used standard methodologic procedures expected by Cochrane. We evaluated treatment effects using a fixed-effect model with risk ratio (RR) and 95% confidence intervals (CI) for categorical data and mean, standard deviation (SD), and mean difference (MD) for continuous data. We used the GRADE approach to evaluate the certainty of evidence.

MAIN RESULTS

We identified one RCT (1858 participants) that met our inclusion criteria. The study included 1858 African newborns at 35 weeks' gestation or greater who were receiving routine care at a well-baby nursery, and were randomly recruited prior to discharge to undergo TcB screening. The study had good methodologic quality. TcB screening versus visual assessment of hyperbilirubinemia in newborns: - may reduce readmission to the hospital for hyperbilirubinemia (RR 0.25, 95% CI 0.14 to 0.46; P < 0.0001; moderate-certainty evidence); - probably has little or no effect on the rate of exchange transfusion (RR 0.20, 95% CI 0.01 to 14.16; low-certainty evidence); - may increase the number of newborns who require phototherapy prior to discharge (RR 2.67, 95% CI 1.56 to 4.55; moderate-certainty evidence). - probably has little or no effect on the rate of acute bilirubin encephalopathy (RR 0.33, 95% CI 0.01 to 8.18; low-certainty evidence). The study did not evaluate or report cost of care.

AUTHORS' CONCLUSIONS

Moderate-certainty evidence suggests that TcB screening may reduce readmission for hyperbilirubinemia compared to visual inspection. Low-certainty evidence also suggests that TcB screening probably has little or no effect on the rate of exchange transfusion compared to visual inspection. However, moderate-certainty evidence suggests that TcB screening may increase the number of newborns that require phototherapy before discharge compared to visual inspection. Low-certainty evidence suggests that TcB screening probably has little or no effect on the rate of acute bilirubin encephalopathy compared to visual inspection. Given that we have only identified one RCT, further studies are necessary to determine whether TcB screening can help to reduce readmission and complications related to neonatal hyperbilirubinemia. In settings with limited newborn follow-up after hospital discharge, identifying newborns at risk of severe hyperbilirubinemia before hospital discharge will be important to plan targeted follow-up of these infants.

Neonatal hyperbilirubinemia and repercussions on neurodevelopment: A systematic review

BACKGROUND

Accumulation of bilirubin above normal levels is considered a neurological risk factor for both premature and full-term newborns. This systematic review aimed to determine the effect of neonatal hyperbilirubinemia on neurodevelopment in preterm and full-term newborns.

METHODS

PubMed, EMBASE, Cochrane Library, CINAHL, PsycINFO, Scopus and Lilacs databases were searched for articles published until 1 June 2022. The quality of cohort and case-control studies was assessed with the Newcastle-Ottawa Scale, and the MINCir scale was used to evaluate the methodological quality of therapy studies or the therapeutic procedures. Premature neonates without neurological conditions and those born at term with hyperbilirubinemia as the sole risk factor were included. Studies reporting one or more neurodevelopmental outcomes were included with an inter-group comparison of a hyperbilirubinemia group versus a non-hyperbilirubinemia or non-pathological hyperbilirubinemia group. The main outcomes were auditory function, visual function, cognitive function, motor function, behavior, global development and neurological risk.

RESULTS

The search identified 951 studies, 19 of which (n = 2210 newborns) were finally included. Fifteen of the cohort and case-control studies presented low risk of bias, and six studies showed high methodological quality. Within the preterm population, hyperbilirubinemia as the sole risk factor was not shown to affect neurodevelopment. Auditory, neurological and motor development alterations were found in the population of full-term newborns with hyperbilirubinemia, which were more evident during the first year of life.

CONCLUSIONS

Elevated bilirubin levels may be a trigger for the onset of neurodevelopmental disorders in full-term infants during the first year of life. More studies are warranted in the preterm population with hyperbilirubinemia to draw conclusions about its impact on their neurodevelopment.

Updated Clinical Practice Guidelines for Management of Hyperbilirubinemia in Infants Born at 35 Weeks or More Gestation

Given the prevalence of jaundice in newborns, and the consequences of untreated hyperbilirubinemia, the long-awaited revised clinical practice guidelines for hyperbilirubinemia were finally released in August 2022 by the American Academy of Pediatrics as an update to the 2004 guidelines on the same topic. As new evidence and data become available, it is important for pediatricians and neonatologists to re-assess their clinical decision-making over time to ensure that patients are receiving the best care possible. With improvements in medical equipment and medical technology, and growing concerns about the overtreatment of hyperbilirubinemia, the newest clinical practice guidelines attempt to tackle the prevention, risk assessment, monitoring, and treatment of hyperbilirubinemia with these things in mind. [Pediatr Ann. 2023;52(12):e436-e439.].

Prospective cohort study of neurodevelopmental outcomes following extreme neonatal hyperbilirubinaemia in Australia

AIM

This study aimed to establish the incidence and nature of neurodevelopmental outcomes following extreme neonatal hyperbilirubinaemia in an Australian cohort.

METHODS

A prospective cohort study of neurodevelopmental outcomes up to 3 years of age of infants born between 2010 and 2013 at ≥34 weeks gestation, with total serum bilirubin ≥450 μmol/L and/or clinical signs of acute bilirubin encephalopathy. Outcome measures comprised neurological examination, Bayley Scales of Infant and Toddler Development, 3rd edition and Ages and Stages Questionnaire, 3rd edition.

RESULTS

The Australian estimated incidence of kernicterus is 0.35 per 100 000 live births. Within the follow-up cohort of 26, three children have clinical neurodevelopmental impairment: one has gross motor function classification system level 4 cerebral palsy, audiological deficiency and visual impairment; the second has gross motor function classification system level 1 cerebral palsy and the third has global developmental delay with autism spectrum disorder. Mean Bayley Scales of Infant and Toddler Development, 3rd edition scores were: cognition 10.3 (SD 1.5), receptive communication 9.4 (SD 1.8), expressive communication 9.2 (SD 2.4), fine motor 10.4 (SD 2.6) and gross motor 9.2 (SD 2.3).

CONCLUSION

The Australian national rate of kernicterus compares favourably with global estimates. Future preventative strategies in this context include universal neonatal hyperbilirubinaemia assessment and mandated adverse outcome reporting and investigation.

Globus pallidus/putamen T1WI signal intensity ratio in grading and predicting prognosis of neonatal acute bilirubin encephalopathy

Purpose

This study sought to investigate the relationship between the globus pallidus/putamen T1 weighted image (T1WI) signal intensity ratio (G/P ratio) and the acute bilirubin encephalopathy (ABE) in neonates, and to develop a new strategy for the grading and prognosis of ABE based on the G/P ratio.

Methods

A total of 77 full-term neonates with ABE were scored according to bilirubin-induced neurological dysfunction and divided into mild, moderate, and severe groups. Cranial magnetic resonance imaging examinations were performed and the G/P ratio was recorded. The follow-up reexaminations were carried out at 6 months, 1 year, and 2 years after the initial examination. The neonates were then divided into two groups, the good prognosis group and the kernicterus spectrum disorder (KSD) group, according to the evaluation of Gesell Developmental Schedules and Brainstem Audio Electric Potential at 6 months.

Main findings

The differences of G/P ratios were statistically significant, not only among the mild, moderate, and severe ABE groups for the initial examinations but also between the KSD and the good prognosis groups for the follow-up reexaminations. Therefore, the ABE grading model and prognosis predicting model could be established based on the G/P ratio. In the KSD group, the area under the receiver operating characteristic curve of the G/P ratio-based predicting model was 93.5%, the optimal critical point was 1.29, the sensitivity was 88.2%, and the specificity was 93.3%.

Conclusions

The G/P ratio can be used as an indicating parameter for both the clinical grading of neonatal ABE and the assessment of neonatal ABE prognosis. Specifically, the G/P ratio greater than 1.29 indicates a KSD of neonatal ABE.

Implementing Higher Phototherapy Thresholds for Jaundice in Healthy Infants 35 Plus Weeks

OBJECTIVES

To determine the impact of higher bilirubin thresholds on testing and treatment of healthy infants during the neonatal period.

METHODS

This quality improvement study included infants born at ≥35 weeks gestation and admitted to the well-baby nursery between July 2018 and December 2020. We assessed the transition from infants treated according to the 2004 AAP guidelines (pregroup) with those following the Northern California Neonatal Consortium guidelines (postgroup). We examined the proportion of infants receiving phototherapy and total serum bilirubin (TSB) assessments as outcome measures. We examined critical hyperbilirubinemia (TSB above 25 mg/dL or TSB within 2 mg/dL of threshold for exchange transfusion), exchange transfusion, and readmission for jaundice as balancing measures. We compared the differences in outcomes over time using Statistical Process Control p charts. Balancing measures between the pre and postgroups were compared using χ square tests and t-tests.

RESULTS

In our population of 6173 babies, there was a significant shift in the proportion receiving phototherapy from 6.4% to 4%. There were no significant changes in incidences of bilirubin >25 mg/dL (0 of 1472 vs 7 of 4709, P = .37), bilirubin within 2 mg/dL of exchange transfusion thresholds (4 of 1472 vs 5 of 4709, P = .15), exchange transfusion (0 of 1472 vs 1 of 4709, P = .70) or readmission for phototherapy (2.9% versus 2.4%, P = .30), between the 2 groups.

CONCLUSIONS

Higher thresholds for phototherapy treatment of neonatal hyperbilirubinemia can decrease the need for phototherapy without increasing critical hyperbilirubinemia or readmission rate.

Technical Report: Diagnosis and Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation

CONTEXT

Severe hyperbilirubinemia is associated with kernicterus. Informed guidance on hyperbilirubinemia management, including preventive treatment thresholds, is essential to safely minimize neurodevelopmental risk.

OBJECTIVE

To update the evidence base necessary to develop the 2022 American Academy of Pediatrics clinical practice guideline for management of hyperbilirubinemia in the newborn infant ≥35 weeks' gestation.

DATA SOURCE

PubMed.

STUDY SELECTION

English language randomized controlled trials and observational studies. Excluded: case reports or series, nonsystematic reviews, and investigations focused on <35-weeks' gestation infants.

DATA EXTRACTION

Topics addressed in the previous clinical practice guideline (2004) and follow-up commentary (2009) were updated with new evidence published through March 2022. Evidence reviews were conducted for previously unaddressed topics (phototherapy-associated adverse effects and effectiveness of intravenous immune globulin [IVIG] to prevent exchange transfusion).

RESULTS

New evidence indicates that neurotoxicity does not occur until bilirubin concentrations are well above the 2004 exchange transfusion thresholds. Systematic review of phototherapy-associated adverse effects found limited and/or inconsistent evidence of late adverse effects, including cancer and epilepsy. IVIG has unclear benefit for preventing exchange transfusion in infants with isoimmune hemolytic disease, with a possible risk of harm due to necrotizing enterocolitis.

LIMITATIONS

The search was limited to 1 database and English language studies.

CONCLUSIONS

Accumulated evidence justified narrowly raising phototherapy treatment thresholds in the updated clinical practice guideline. Limited evidence for effectiveness with some evidence of risk of harm support the revised recommendations to limit IVIG use.

Long-Term Mental Health and Quality of Life Outcomes of Neonatal Insults in Kilifi, Kenya

We examined the mental health and quality of life (QoL) outcomes and their correlates of school-aged survivors of neonatal jaundice (NNJ), hypoxic-ischemic encephalopathy (HIE), and a comparison group. The Child Behavior Checklist and the Pediatric Quality of Life Inventory were administered to assess the mental health and QoL of 375 children (134 with NNJ, 107 with HIE, and 134 comparison group) aged 6 to 12 years [Median age 9 (interquartile range 7 to 11)]. The results showed that survivors of NNJ and HIE have mental health problems and QoL similar to the comparison group. Maternal mental health was the predominant covariate of mental health and QoL in survivors of NNJ and HIE. This result could indicate that mothers with mental health problems are more likely to have children with mental health issues, but also that caring for children with these adversities may affect mental health well-being of the caregivers. There is a need for early mental health screening and psychosocial intervention for caregivers and their children to enhance both their mental health and QoL.

Early Neurodevelopmental Outcome of Neonates with Gestation 35 Weeks or More with Serum Bilirubin in Exchange Range Without Encephalopathy: A Prospective Observational Study

OBJECTIVE

To describe early neurodevelopment outcomes of neonates with severe hyperbilirubinemia without acute bilirubin encephalopathy (ABE).

METHODS

Neonates born at gestation ≥35 weeks, admitted to NICU with total serum bilirubin (TSB) in exchange range with no features of ABE, were followed up until the age of 6 months. Infants were assessed for impaired hearing and neurodevelopment at 3 months and 6 months of age.

RESULTS

A total of 59 neonates were enrolled in the study. At 3 months of age, 7.6 percent of neonates were found to have hypotonia and motor delay, whereas 42.3 percent had abnormal brainstem evoked response audiometery. At 6 months, 6.4 percent of neonates were found to have persistent neurodevelopmental impairment.

CONCLUSION

Severe hyperbilirubinemia is associated with impaired neurodevelopment and hearing even in infants without ABE. Peak TSB level strongly correlates with abnormal outcomes.

Neurodevelopmental outcome of healthy term newborn with serum bilirubin >15 mg/dl at one year

BACKGROUND

Neonatal hyperbilirubinemia is a common medical emergency in early neonatal period. Unconjugated bilirubin is neurotoxic and can lead to lifelong neurological sequelae in survivors.

OBJECTIVE

To find out the association between serum bilirubin and neurodevelopmental outcome at 1 year of age using Development Assessment Scale for Indian Infants (DASII).

METHODS

A prospective cohort study was conducted in the Department of Pediatrics of a tertiary care institution of Central India between January 2018 and August 2019. Total 108 term healthy neonates, with at least one serum bilirubin value of >15 mg/dl, were included. Subjects were divided into three groups based on the serum bilirubin; group 1: (15-20 mg/dl) -85(78.7%) cases, group 2: (20-25 mg/dl) -17(15.7%), and group 3: (>25 mg/dl) -6(5.5%). Developmental assessment was done using DASII at 3, 6, 9, 12 months of age.

RESULTS

Out of 108 cases, 101(93.5%) received phototherapy, and 7(6.5%) received double volume exchange transfusion. Severe delay was observed in 5(4.6%) and mild delay in 2(1.9%) cases in the motor domain of DASII at one year. Severe delay in the motor domain was associated with mean TSB of 27.940±2.89 mg/dl and mild delay with mean TSB of 22.75±1.76 mg/dl (p = 0.001). On cluster analysis, delay was observed in locomotion 1 score in 11(13%) cases (p = 0.003) and manipulation score in 6(7.1%) cases in group 1.

CONCLUSION

Increased serum bilirubin was a significant risk factor for the delayed neurodevelopment in babies with neonatal jaundice. Even a moderate level of bilirubin significantly affects the developmental outcome.

Unbound bilirubin measurements in term and late-preterm infants

Background: Hyperbilirubinemia occurs in over 80% of newborns, and severe bilirubin toxicity can lead to neurological dysfunction and death. Unbound bilirubin (Bf) levels predict the risk of neurodevelopmental handicap, although total serum bilirubin (TSB) is used to manage care.Objective: To measure Bf levels in healthy infants, its relationship to TSB, and its response to phototherapy. We hypothesize unexpectedly high Bf levels, poor correlation with TSB and unpredictable response to phototherapy.Design/methods: Healthy infants were studied with simultaneous TSB and Bf measurements. The clinical data recorded included ethnicity, gender, birth weight, gestational age, and mode of delivery, Apgar scores, breast/formula feeds, and phototherapy.Results: One hundred thirty-two infants (3248.9 ± 509.2g, GA 38.7 ± 1.4 weeks), at mean age of the initial sample of 28.5 ± 15.6 h, had a TSB of 7.9 ± 2.7 mg/dl, and a Bf of 5.2 ± 3.2 nM. The correlation between Bf and TSB was significant but not between Bf and TSB for TSB >12 mg/dl. Bf >11nm were in 22.7% and >17 nM in 3.8% of infants. Post-phototherapy TSB and Bf levels were similar to those before treatment.Conclusions: The relationship between TSB and Bf in healthy infants is complex, with the inability of one to predict the other's level in infants with elevated TSB. The mechanism of bilirubin-related neurotoxicity suggests that the management of jaundice in healthy infants requires Bf measurements. Management of jaundice with TSB may result in more infants exposed to phototherapy. However, unexpected elevations of Bf occur in an apparently healthy population.

The spectrum of bilirubin neurotoxicity in term and near-term babies with hyperbilirubinemia: Does outcome improve with time?

BACKGROUND

While neonatal jaundice is generally a common benign condition; severe hyperbilirubinemia has a devastating potential for brain injury.

AIM

To detect the impact of severe neonatal hyperbilirubinemia on motor and mental development and its progress over time in the first year of life using the Bayley scales of infant development (BSID) II.

STUDY DESIGN AND PATIENTS

177 term/near-term infants admitted for neonatal hyperbilirubinemia to the NICU of Cairo University Children's Hospital were enrolled. Clinical examination, BIND score and laboratory tests were performed at admission. Neurodevelopmental assessment using BSIDΙΙ was performed at 3 months for 147/177 neonates, and at 6 months and 12 months for 139/177 neonates. Auditory brainstem evoked potential was recorded at 3 months of age and repeated if abnormal.

OUTCOME MEASURES

Psychomotor (PDI) and mental developmental indices (MDI) using BSIDII. Auditory impairment using Auditory Brainstem Response (ABR).

RESULTS

TSB levels ranged from 10 to 63 mg/dL (179.6-1077 μmol/L) with a mean of 25.52 ± 6.5 mg/dL (436 ± 112.9 μmol/L) and BIND scores ranged from 0 to 7. By one year of age, 19/139 patients were affected; 8 had classic kernicterus, 3 had isolated auditory impairment, 1 had severe motor and mild mental delay and 7 had mild motor delay. TSB level and BIND score had positive correlation with auditory impairment and lower scores for PDI (which improved with time) and MDI (which remained stationary). Duration of exposure to hyperbilirubinemia negatively affected neurodevelopmental scores.

CONCLUSION

The impact of severe hyperbilirubinemia is mainly on motor and auditory impairment. Mild mental delay was detected by BSIDII in few patients. Neurodevelopmental outcome improves over time.

Rates of Extreme Neonatal Hyperbilirubinemia and Kernicterus in Children and Adherence to National Guidelines for Screening, Diagnosis, and Treatment in Sweden

IMPORTANCE

Neonatal hyperbilirubinemia can cause lifelong neurodevelopmental impairment (kernicterus) even in high-resource settings. A better understanding of the incidence and processes leading to kernicterus may help in the design of preventive measures.

OBJECTIVES

To determine incidence rates of hazardous hyperbilirubinemia and kernicterus among near-term to term newborns and to evaluate health care professional adherence to best practices.

DESIGN, SETTING, AND PARTICIPANTS

This population-based nationwide cohort study used prospectively collected data on the highest serum bilirubin level for all infants born alive at 35 weeks' gestation or longer and admitted to neonatal care at all 46 delivery and 37 neonatal units in Sweden from 2008 to 2016. Medical records for newborns with hazardous hyperbilirubinemia were evaluated for best neonatal practices and for a diagnosis of kernicterus up to 2 years of age. Data analyses were performed between September 2017 and February 2018.

EXPOSURES

Extreme (serum bilirubin levels, 25.0-29.9 mg/dL [425-509 μmol/L]) and hazardous (serum bilirubin levels, ≥30.0 mg/dL [≥510 μmol/L]) neonatal hyperbilirubinemia.

MAIN OUTCOMES AND MEASURES

The primary outcome was kernicterus, defined as hazardous neonatal hyperbilirubinemia followed by cerebral palsy, sensorineural hearing loss, gaze paralysis, or neurodevelopmental retardation. Secondary outcomes were health care professional adherence to national guidelines using a predefined protocol with 10 key performance indicators for diagnosis and treatment as well as assessment of whether bilirubin-associated brain damage might have been avoidable.

RESULTS

Among 992 378 live-born infants (958 051 term births and 34 327 near-term births), 494 (320 boys; mean [SD] birth weight, 3505 [527] g) developed extreme hyperbilirubinemia (50 per 100 000 infants), 6.8 per 100 000 infants developed hazardous hyperbilirubinemia, and 1.3 per 100 000 infants developed kernicterus. Among 13 children developing kernicterus, brain injury was assessed as potentially avoidable for 11 children based on the presence of 1 or several of the following possible causes: untimely or lack of predischarge bilirubin screening (n = 6), misinterpretation of bilirubin values (n = 2), untimely or delayed initiation of treatment with intensive phototherapy (n = 1), untimely or no treatment with exchange transfusion (n = 6), or lack of repeated exchange transfusions despite indication (n = 1).

CONCLUSIONS AND RELEVANCE

Hazardous hyperbilirubinemia in near-term or term newborns still occurs in Sweden and was associated with disabling brain damage in 13 per million births. For most of these cases, health care professional noncompliance with best practices was identified, suggesting that a substantial proportion of these cases might have been avoided.

Characteristics and outcome of newborn admitted with acute bilirubin encephalopathy to a tertiary neonatal intensive care unit

BACKGROUND

Acute bilirubin encephalopathy (ABE) still represents a significant cause of morbidity and mortality throughout the world, especially in developing countries. We aimed to determine the prevalence of ABE based on the Johnson bilirubin-induced neurologic dysfunction (BIND) score and to describe the discharge outcomes.

METHODS

We prospectively studied all newborns ≥ 35 weeks with ABE by evaluating signs of mental sensorium, muscle tone, and cry patterns over 1 year.

RESULTS

12% (81 out of 674) of the newborns admitted for neonatal hyperbilirubinemia had a BIND score > 1. Their admission age was 6 ± 4.1 days; total serum bilirubin (TSB) was 31.2 ± 10 mg/dL (range 17.5-75.2). Of these newborns, 40.7% and 21% had evidence of haemolysis and sepsis, respectively. Overall mortality was 9.9%; 58% of the newborns showed signs of mild-to-moderate BIND at discharge, while 32.1% survived with an apparently normal outcome. Admission BIND score was significantly correlated with admission TSB (r = 0.476, P < 0.001). Similarly, BIND score at discharge was correlated with admission TSB (r = 0.442, P < 0.001) and admission BIND score (r = 0.888, P < 0.001). The regression model showed that admission TSB (P < 0.001) and maternal illiteracy (P = 0.034) were predictors of the BIND score at admission, while admission BIND score was the best indicator of the discharge score (P < 0.001).

CONCLUSIONS

ABE is still a major problem in our community. Admission TSB and maternal illiteracy are good predictors of bilirubin encephalopathy at admission and discharge.

High unbound bilirubin for age: a neurotoxin with major effects on the developing brain

Neonatal hyperbilirubinemia is one of the most frequent diagnoses made in neonates. A high level of unconjugated bilirubin that is unbound to albumin is neurotoxic when the level exceeds age-specific thresholds or at lower levels in neonates with neurotoxic risk factors. Lower range of unbound bilirubin results in apoptosis, while moderate-to-high levels result in neuronal necrosis. Basal ganglia and various brain stem nuclei are more susceptible to bilirubin toxicity. Proposed mechanisms of bilirubin-induced neurotoxicity include excessive release of glutamate, mitochondrial energy failure, release of proinflammatory cytokines, and increased intracellular calcium concentration. These mechanisms are similar to the events that occur following hypoxic-ischemic insult in neonates. Severe hyperbilirubinemia in term neonates has been shown to be associated with increased risk for autism spectrum disorders. The neuropathological finding of bilirubin-induced neurotoxicity also includes cerebellar injury with a decreased number of Purkinje cells, and disruption of multisensory feedback loop between cerebellum and cortical neurons which may explain the clinical characteristics of autism spectrum disorders. Severe hyperbilirubinemia occurs more frequently in infants from low- and middle-income countries (LMIC). Simple devices to measure bilirubin, and timely treatment are essential to reduce neurotoxicity, and improve outcomes for thousands of neonates around the world.

Developmental influence of unconjugated hyperbilirubinemia and neurobehavioral disorders

Bilirubin-induced brain injury in the neonatal period has detrimental effects on neurodevelopment that persist into childhood and adulthood, contributing to childhood developmental disorders. Unconjugated bilirubin is a potent antioxidant that may be useful for protecting against oxidative injuries, but it becomes a potent neurotoxin once it crosses the blood brain barrier. Because bilirubin toxicity involves a myriad of pathological mechanisms, can damage most types of brain cells, and affects brain circuits or loops that influence cognition, learning, behavior, sensory, and language, the clinical effects of bilirubin-induced neurotoxicity are likely to be manifold. One possible effect that several experts have identified is bilirubin-induced neurological dysfunction (subtle kernicterus). However, the underlying biological mechanisms or pathways by which subtle kernicterus could lead to developmental disorders has not been elucidated previously. Our aim in this review is to describe a spectrum of developmental disorders that may reflect subtle kernicterus and outline plausible biological mechanisms for this possible association. We review existing evidence that support or refute the association between unconjugated hyperbilirubinemia and developmental disorders, and limitations associated with these studies.

Follow-up of Children with Kernicterus in Kano, Nigeria

INTRODUCTION

Acute bilirubin encephalopathy (ABE) is associated with long-term sequelae (kernicterus). It continues to be a significant issue in our region of Nigeria, accounting for much morbidity and mortality. Herein we report the outcome of neonates with ABE seen at our centre.

METHODOLOGY

We established a surveillance of children who had ABE and returned to follow-up from prospective cases of ABE (2012-2014). ABE was diagnosed based on a bilirubin-induced neurologic dysfunction score of ≥ 1. Kernicterus was subsequently established based on a history of developmental delays, hearing impairments and abnormal physical and neurologic examinations at follow-up age ≥3 months.

RESULT

Five hundred fifty-one neonates had hyperbilirubinaemia of whom 104 (18.8%) had ABE. Mean transcutaneous bilirubin using the Ingram icterometer was 18.3 mg/dl  ±  SD 1.9 [(12.5-19.1), total serum bilirubin of 18.1 ± 10.9] (range: 10.3-64 mg/dl). Sixty-five infants returned for follow-up (41 males and 24 females); mean age 9 months (22 days to 17 months). Most (58 of 65; 89.2%) had abnormal neurological findings and 15 (25.9%) had probable kernicterus.

CONCLUSION

There is a critical need for a National Kernicterus Registry to document all cases of kernicterus and formulate an effective treatment and prevention policy.

Systemic regulation of bilirubin homeostasis: Potential benefits of hyperbilirubinemia

Neurotoxic bilirubin is the end product of heme catabolism in mammals. Bilirubin is solely conjugated by uridine diphospho-glucuronosyltransferase 1A1, which is a membrane-bound enzyme that catalyzes the transfer of glucuronic acid. Due to low function of hepatic and intestinal uridine diphospho-glucuronosyltransferase 1A1 during the neonatal period, human neonates develop mild to severe physiological hyperbilirubinemia. Accumulation of bilirubin in the brain leads to the onset of irreversible brain damage, termed kernicterus. Breastfeeding is one of the most significant factors that increase the risk of developing kernicterus in infants. Why does this most natural way of feeding increase the risk of brain damage or even death? This question leads to the hypothesis that breast milk-induced hyperbilirubinemia might bring certain benefits that outweigh those risks. While bilirubin is neurotoxic and cytotoxic, this compound is also a potent antioxidant. There are studies showing improved clinical conditions in patients with hyperbilirubinemia. Accumulating evidence also shows that genetic polymorphisms linked to hyperbilirubinemia are beneficial against various diseases. In this review article, we first introduce the production, metabolism, and transport of bilirubin. We then discuss the potential benefits of neonatal and adult hyperbilirubinemia. Finally, epigenetic factors as well as metabolomic information associated with hyperbilirubinemia are described. This review article advances the understanding of the physiological importance of the paradoxical compound bilirubin. (Hepatology 2018;67:1609-1619).

Unbound bilirubin measurements by a novel probe in preterm infants

BACKGROUND

Hyperbilirubinemia occurs in over 80% of newborns and severe bilirubin toxicity can lead to neurological dysfunction and death, especially in preterm infants. Currently, the risk of bilirubin toxicity is assessed by measuring the levels of total serum bilirubin (TSB), which are used to direct treatments including immunoglobulin administration, phototherapy, and exchange transfusion. However, free, unbound bilirubin levels (Bf) predict the risk of bilirubin neurotoxicity more accurately than TSB.

OBJECTIVE

To examine Bf levels in preterm infants and determine the frequency with which they exceed reported neurotoxic thresholds.

METHODS

One hundred thirty preterm infants (BW 500-2000 g; GA 23-34 weeks) were enrolled and Bf levels measured during the first week of life by the fluorescent Bf sensor BL22P1B11-Rh. TSB and plasma albumin were measured by standard techniques. Bilirubin-albumin dissociation constants (K_d) were calculated based on Bf and plasma albumin.

RESULTS

Five hundred eighty samples were measured during the first week of life, with an overall mean Bf of 13.6 ± 9.0 nM. A substantial number of measurements exceeded potential toxic thresholds levels as reported in the literature. The correlation between Bf and TSB was statistically significant (r² 0.17), but this weak relationship was lost at high Bf levels. Infants <28-week gestations had more hearing screening failures than infants ≥28-week gestation.

CONCLUSIONS

Unbound (free) bilirubin values are extremely variable during the first week of life in preterm infants. A significant proportion of these values exceeded reported neurotoxic thresholds.

Hyperbilirubinemia Influences Sleep-Wake Cycles of Term Newborns in a Non-Linear Manner

Hyperbilirubinemia is a common cause for irreversible neuronal influence in the brain of term newborns, while the feature of neurological symptoms associated with hyperbilirubinemia has not been well characterized yet. In the present study, we examined a total of 203 neonates suffering from hyperbilirubinemia with a bedside amplitude-integrated Electroencephalography (aEEG) device, in order to determine whether there is any special change in sleep-wake cycles (SWCs). Among these patients, 14 cases showed no recognizable SWCs with the total serum bilirubin (TSB) level at 483.9–996.2 μmol/L; 75 cases exhibited reduced SWCs with the TSB level at 311.2–688.5 μmol/L; and the rest cases had the normal SWCs. The number of the normal SWCs occurrence had a significant negative correlation with the increased TSB level in a non-linear manner (r = -0.689, p <0.001). In addition, the increased TSB reshaped the structure of SWC by narrowing down the broadband and broadening the narrowband. Spearman’s correlation analysis indicated a significant negative correlation between the TSB level and the ratio of broadband (r = -0.618, p < 0.001), a significant positive correlation between the TSB level and the narrowband ratio (r = 0.618, p < 0.001), respectively. Furthermore, the change of SWC seemed like a continuous phenomenon, and the hyperbilirubinemia caused SWC changes was fit into a loess model in this paper. In summary, the hyperbilirubinemia influenced SWC of term newborns significantly at a non-linear manner, and these results revealed the feature of the neurological sequela that is associated with TSB.

A Hypothesis for Using Pathway Genetic Load Analysis for Understanding Complex Outcomes in Bilirubin Encephalopathy

Genetic-based susceptibility to bilirubin neurotoxicity and chronic bilirubin encephalopathy (kernicterus) is still poorly understood. Neonatal jaundice affects 60–80% of newborns, and considerable effort goes into preventing this relatively benign condition from escalating into the development of kernicterus making the incidence of this potentially devastating condition very rare in more developed countries. The current understanding of the genetic background of kernicterus is largely comprised of mutations related to alterations of bilirubin production, elimination, or both. Less is known about mutations that may predispose or protect against CNS bilirubin neurotoxicity. The lack of a monogenetic source for this risk of bilirubin neurotoxicity suggests that disease progression is dependent upon an overall decrease in the functionality of one or more essential genetically controlled metabolic pathways. In other words, a “load” is placed on key pathways in the form of multiple genetic variants that combine to create a vulnerable phenotype. The idea of epistatic interactions creating a pathway genetic load (PGL) that affects the response to a specific insult has been previously reported as a PGL score. We hypothesize that the PGL score can be used to investigate whether increased susceptibility to bilirubin-induced CNS damage in neonates is due to a mutational load being placed on key genetic pathways important to the central nervous system's response to bilirubin neurotoxicity. We propose a modification of the PGL score method that replaces the use of a canonical pathway with custom gene lists organized into three tiers with descending levels of evidence combined with the utilization of single nucleotide polymorphism (SNP) causality prediction methods. The PGL score has the potential to explain the genetic background of complex bilirubin induced neurological disorders (BIND) such as kernicterus and could be the key to understanding ranges of outcome severity in complex diseases. We anticipate that this method could be useful for improving the care of jaundiced newborns through its use as an at-risk screen. Importantly, this method would also be useful in uncovering basic knowledge about this and other polygenetic diseases whose genetic source is difficult to discern through traditional means such as a genome-wide association study.

Informed Consent Should Be a Required Element for Newborn Screening, Even for Disorders with High Benefit-Risk Ratios

Over-enthusiastic newborn screening has often caused substantial harm and has been imposed on the public without adequate information on benefits and risks and without parental consent. This problem will become worse when genomic screening is implemented. For the past 40 years, there has been broad agreement about the criteria for ethically responsible screening, but the criteria have been systematically ignored by policy makers and practitioners. Claims of high benefit and low risk are common, but they require precise definition and documentation, which has often not occurred, undermining claims that involuntary testing is justified. Even when the benefits and risks are well established, it does not automatically follow that involuntary testing is justified, a position supported by the widespread tolerance for parental refusal of immunizations and newborn screening.

Retrospective Cohort Study of Phototherapy and Childhood Cancer in Northern California

OBJECTIVE

To investigate the association between neonatal phototherapy use and childhood cancer.

METHODS

This retrospective cohort study included 499 621 children born at ≥35 weeks' gestation from 1995 to 2011 in Kaiser Permanente Northern California hospitals, who survived to hospital discharge and were followed ≥60 days. We obtained data on home and inpatient phototherapy, covariates, and cancer incidence from electronic records. We used propensity-adjusted Cox and Poisson models to control for confounding and unequal follow-up times.

RESULTS

There were 60 children with a diagnosis of cancer among 39 403 exposed to phototherapy (25 per 100 000 person-years), compared with 651 of 460 218 unexposed children (18 per 100 000 person-years; incidence rate ratio [IRR] 1.4; P = .01). Phototherapy was associated with increased rates of any leukemia (IRR 2.1; P = .0007), nonlymphocytic leukemia (IRR 4.0; P = .0004), and liver cancer (IRR 5.2; P = .04). With adjustment for a propensity score that incorporated bilirubin levels, chromosomal disorders, congenital anomalies, and other covariates, associations were no longer statistically significant: Adjusted hazard ratios (95% confidence intervals) were 1.0 (0.7-1.6) for any cancer, 1.6 (0.8-3.5) for any leukemia, 1.9 (0.6-6.9) for nonlymphocytic leukemia, and 1.4 (0.2-12) for liver cancer. Upper limits of 95% confidence intervals for adjusted 10-year excess risk were generally <0.1% but reached 4.4% for children with Down syndrome.

CONCLUSIONS

Although phototherapy use was associated with increased cancer rates (particularly nonlymphocytic leukemia), control for confounding variables eliminated or attenuated the associations. Nonetheless, the possibility of even partial causality suggests that avoiding unnecessary phototherapy may be prudent.

Atazanavir exposure in utero and neurodevelopment in infants: a comparative safety study

OBJECTIVE

To evaluate the safety of in-utero exposure to atazanavir and neurodevelopment in perinatally HIV-exposed but uninfected (PHEU) infants.

DESIGN

Prospective cohort study of mother-PHEU infant pairs in the Surveillance Monitoring for ART Toxicities protocol of the Pediatric HIV/AIDS Cohort Study.

METHODS

Pregnant women living with HIV who initiated an antiretroviral regimen during pregnancy were followed from the date of antiretroviral initiation. Women were classified according to whether the antiretroviral regimen contained atazanavir and the trimester of antiretroviral initiation. Neurodevelopment at 9-15 months was evaluated using the Bayley Scales of Infant and Toddler Development-Third Edition (Bayley-III). We estimated mean differences for the five Bayley-III domains for atazanavir-containing regimens versus all other regimens. Models included baseline covariates and adjustment for failure to complete the Bayley-III using inverse probability weighting.

RESULTS

PHEU infants were exposed in utero to atazanavir-containing (n = 167) and nonatazanavir-containing (n = 750) antiretroviral regimens. The adjusted mean differences (95% confidence interval) in Bayley-III domain scores for initiating an atazanavir-containing regimen in the first trimester were: cognitive, -1.5 (-6.2, 3.2); language, -3.3 (-7.6, 1.0); motor, -2.9 (-7.7, 1.9); social-emotional, 0.1 (-6.2, 6.4); and adaptive behavior, -0.1 (-4.3, 4.0). The mean differences for the second or third trimester were: cognitive, 0.4 (-3.2, 4.0); language, -3.4 (-6.2, -0.5); motor, 0.3 (-2.9, 3.4); social-emotional, -5.9 (-9.4, -2.3); and adaptive behavior, -2.5 (-5.9, 0.8).

CONCLUSION

In-utero exposure to atazanavir-containing regimens compared with non-atazanavir-containing regimens may adversely affect language and social-emotional development in PHEU infants during the first year of life, but the absolute difference is small.

Phototherapy for the Treatment of Neonatal Jaundice and Breastfeeding Duration and Exclusivity

INTRODUCTION

Because neonatal jaundice remains one of the most commonly treated conditions of the newborn infant, it is important to assess the unintended consequences of treatment with phototherapy. The objective of this study was to evaluate whether treatment with phototherapy affects breastfeeding duration in newborns >35 weeks gestation.

MATERIALS AND METHODS

We analyzed data from the Infant Feeding Practices Study II. The exposure of interest was treatment of neonatal jaundice with phototherapy. The outcomes of interest were any breastfeeding through 12 months and exclusive breastfeeding through 4 months. Logistic regression models were developed to evaluate the association between the exposure and outcomes of interest. All models were adjusted for maternal age, race, education, household income, and gestational age, as well as for several potential markers of suboptimal breastfeeding.

RESULTS

Our study included 4,441 infants, of which 220 (5%) received phototherapy. We found no difference in the likelihood of any breastfeeding through 9 months of age, however, by 12 months, infants exposed to phototherapy were less likely to still be breastfed than those who were not exposed (adjusted odds ratio [aOR] 0.58, 95% confidence interval [95% CI] 0.37-0.92). Infants exposed to phototherapy were less likely to be exclusively breastfed throughout the first 4 months of life.

CONCLUSION

Although phototherapy use did not substantially impact rates of any breastfeeding during the first year, it was associated with decreased rates of exclusive breastfeeding in the first 4 months of life. This suggests that we need to tailor messaging to mothers of infants receiving phototherapy to promote exclusive breastfeeding.

Revisiting the Criteria for Exchange Transfusion for Severe Neonatal Hyperbilirubinemia in Resource-Limited Settings

BACKGROUND

Exchange transfusion (ET) for severe neonatal hyperbilirubinemia (SNH) is frequently undertaken in low- and middle-income countries (LMIC), in sharp contrast to the prevailing practice in high-income countries. However, the criteria for initiating this procedure in settings with limited resources for treating infants with SNH have not been systematically explored.

OBJECTIVE

To identify key considerations for initiating ET in resource-poor countries to curtail its unnecessary use for the prevention of kernicterus.

METHODS

A review of the existing guidelines and literature on the management of neonatal hyperbilirubinemia worldwide was conducted to identify criteria and underlying factors for initiating ET.

RESULTS

There is a dearth of evidence from randomized clinical trials to support clear criteria for indicated ET worldwide. Because risk assessment for kernicterus based solely on the levels of total serum bilirubin (TSB) has often proved inadequate, a combination of plasma/serum bilirubin estimation and clinical evaluation for acute bilirubin encephalopathy (ABE) has been recommended for predicting the risk of kernicterus. However, there is a lack of consistency regarding the TSB levels for which ET should be initiated in relation to the clinical signs/symptoms of ABE and hemolytic disorders.

CONCLUSIONS

A decision-making framework that combines TSB thresholds and evidence of neurotoxicity is needed for evaluating the risk of kernicterus and prioritising infants for ET in LMICs to curtail unnecessary interventions.

Predicting Nonhemolytic Neonatal Hyperbilirubinemia

BACKGROUND

Before hospital discharge, newborn infants should be assessed for the risk of excessive hyperbilirubinemia. We determined maternal and obstetric risk factors for hyperbilirubinemia in infants born at term (gestational age ≥37 weeks) to form an individualized risk assessment tool for clinical use.

METHODS

This was a population-based study with data from the Swedish Medical Birth Register from 1999 to 2012, including 1,261,948 singleton infants. Outcome was defined as infants diagnosed with hyperbilirubinemia (N = 23,711), excluding all cases of hemolytic (immune-mediated or other specified hemolytic) diseases of the newborn.

RESULTS

Risk factors with an adjusted odds ratio (aOR) for neonatal hyperbilirubinemia of ≥1.5 (medium-sized effect or more) were gestational age 37 to 38 weeks (aOR = 2.83), failed vacuum extraction (aOR = 2.79), vacuum extraction (aOR = 2.22), Asian mother (aOR = 2.09), primipara (aOR = 2.06), large-for-gestational-age infant (aOR = 1.84), obese mother (aOR = 1.83), and small-for-gestational-age infant (aOR = 1.66). Planned cesarean delivery (CD) was associated with a reduced risk (aOR = 0.45). Without any of these risk factors (normal birth weight infant delivered vaginally at 39 to 41 weeks' gestation by a non-Asian, nonobese, multiparous mother) the rate of nonhemolytic neonatal hyperbilirubinemia was 0.7%. In relation to the combined load of different risk factors, rates of neonatal hyperbilirubinemia ranged from 0.2% to 25%.

CONCLUSIONS

Collection of a few easily available maternal and obstetric risk factors predicts >100-fold variation in the incidence of neonatal hyperbilirubinemia. The information provided herein enables individualized risk prediction with interactions between different risk factors taken into account.

A Model for Predicting Significant Hyperbilirubinemia in Neonates From China

OBJECTIVES

To develop and validate a predischarge risk stratification model by using transcutaneous bilirubin (TcB) values and clinical factors to predict significant postdischarge hyperbilirubinemia in healthy term and late preterm Chinese neonates.

METHODS

In a prospective cohort study, 8215 healthy term and late preterm neonates in 8 hospitals in China underwent TcB measurement at <168 hours of age. TcB percentiles were calculated and used to develop an hour-specific nomogram, and 9 empirically weighted items were used to derive a prediction model. A risk stratification model was developed by combining the TcB nomogram with clinical risk scores to predict significant hyperbilirubinemia, defined as a postdischarge bilirubin level that exceeded the hour-specific recommended threshold value for phototherapy. Data from another 13,157 neonates were used to validate the model.

RESULTS

A TcB nomogram for every 12 hours of the studied interval was constructed from the development set. Gestational age, male gender, history of previous neonate who received phototherapy, bruising, feeding mode, weight loss, and early discharge were predictors of postdischarge significant hyperbilirubinemia. The combination of the TcB nomogram and clinical risk score provided the best prediction of significant hyperbilirubinemia with an area under the curve of 0.95 (95% confidence interval: 0.94-0.95) in the development data set and 0.94 (95% confidence interval: 0.93-0.94) in the validation data set. A risk stratification model with 6 distinct risk levels was developed and validated.

CONCLUSIONS

A risk classification model, combining discharge transcutaneous bilirubin values and clinical risk factors, separated term and late preterm Chinese neonates into 6 risk classes for the timely follow-up of postdischarge hyperbilirubinemia detection.

Meconium Atazanavir Concentrations and Early Language Outcomes in HIV-Exposed Uninfected Infants With Prenatal Atazanavir Exposure

OBJECTIVE

To investigate whether prenatal atazanavir (ATV) exposure, assessed by meconium antiretroviral (ARV) quantification, predicts early child language outcomes. Prenatal ATV exposure previously was associated with poorer language development in 1-year olds.

METHODS

Pregnant women with HIV and their uninfected infants enrolled in the Surveillance Monitoring of Antiretroviral Therapy Toxicities study. Meconium ARV concentrations were quantified by liquid chromatography-tandem mass spectrometry. Language development at 1 year was assessed with MacArthur-Bates Communicative Development Inventory (CDI) and Bayley Scales of Infant and Toddler Development-Third Edition (Bayley-III). Late language emergence was defined as ≥ 1 of 4 CDI scores ≤ 10th percentile for age. Associations between fetal ATV exposure timing and duration, meconium ATV concentration, and language outcomes were evaluated, adjusting for potential confounders.

RESULTS

Through 2013, meconium samples were available from 175 of 432 infants with prenatal ATV exposure. Valid Bayley-III (n = 93) and CDI (n = 106) assessments also were available. After adjustment for potential confounders, higher ATV meconium concentrations were associated with lower late language emergence risk (P = 0.04) and cumulative ATV exposure duration also was associated with higher Bayley-III Language scores (P = 0.03). Maternal ATV duration and initiation week correlated with ATV meconium concentrations (positively and negatively, respectively).

CONCLUSIONS

Higher meconium ATV concentrations were protective against developmental language delays at 1 year, suggesting the importance of fetal ATV detoxification into meconium. This information supports ATV exposure safety for infant language development. ATV is a preferred ARV for pregnant women with HIV, suggesting the importance of ATV safety investigations. Additionally, further pursuit of the influences on language development in HIV-exposed uninfected infants is required.

Association of Autism Spectrum Disorders With Neonatal Hyperbilirubinemia

Autism spectrum disorders (ASD) are a common neurodevelopmental disorder of unknown etiology. Studies suggest a link between autism and neonatal jaundice. A 1:3 matched case–control study was conducted with children enrolled in the Military Health System born between October 2002 and September 2009. Diagnostic and procedure codes were used for identifying ASD and hyperbilirubinemia. Two definitions for hyperbilirubinemia were evaluated: an inpatient admission with a diagnosis of jaundice and treatment with phototherapy. A total of 2917 children with ASD and 8751 matched controls were included in the study. After adjustment, there remained an association between ASD in children and an admission with a diagnosis of jaundice (odds ratio = 1.18; 95% confidence interval = 1.06-1.31; P = .001) and phototherapy treatment (odds ratio = 1.33; 95% confidence interval = 1.04-1.69; P = .008). Children who develop ASD are more likely to have an admission with a diagnosis of jaundice in the neonatal period and more likely to require treatment for this jaundice.

Follow-up of extreme neonatal hyperbilirubinaemia in 5- to 10-year-old children: a Danish population-based study

AIM

To investigate whether infants with neonatal hyperbilirubinaemia but without intermediate or advanced bilirubin encephalopathy develop long-term sequelae, with impairment of motor development, executive function, or hearing.

METHOD

This nested double-cohort study included 167 exposed children (107 males, 60 females) born in Denmark 2000 to 2005 at gestational age ≥35 weeks with a total serum bilirubin ≥450 μmol/L (26.3mg/dL) and 163 age-, sex-, and gestational age-matched unexposed children (103 males, 60 females). The children were examined at a mean age of 7.7 years (SD 1.7y) using the Movement Assessment Battery for Children-Second Edition (MABC-2), pure tone audiometry, and the Behavioural Regulation Inventory of Executive Function (BRIEF) questionnaire.

RESULTS

The follow-up rate was 70% of the eligible infants in the exposed group and 45% in the unexposed group. Mean difference was -0.2 (95% confidence interval [CI] -1.1 to 0.8) in adjusted standard score for MABC-2 and 0.3 (95% CI -2.9 to 3.5) in adjusted BRIEF executive composite standard score. No children had significant hearing impairment or a diagnosis of cerebral palsy, attention-deficit-hyperactive disorder, or autism spectrum disorder recorded in national registries.

INTERPRETATION

No evidence was found of an increased risk of deficits in motor development, executive function, or hearing in children with extreme hyperbilirubinaemia who did not have intermediate or advanced bilirubin encephalopathy.

Transient neonatal hyperthyrotropinemia is a risk factor for developing persistent hyperthyrotropinemia in childhood with repercussion on developmental status

OBJECTIVE

Transient neonatal hyperthyrotropinemia (TNH) is defined as a neonatal abnormality of thyroid function, which reverts to normal at re-examination after 2 weeks of life. The thyroid function of these infants has not been sufficiently studied in terms of the risk of developing persistent hyperthyrotropinemia (PH) in later childhood and its impact on growth and development.

DESIGN

A prospective cohort study included all babies born in our hospital between 2001 and 2006 and screened for hypothyroidism, whose thyroid function was re-examined 6 years later. Exclusion criteria included the following conditions: preterm birth, birth weight <2500 g, Down's syndrome, descendants of mothers with immune thyroid disease, congenital malformations, cardiac, renal, hepatic, and metabolic diseases, and steroid or dopamine medication. The variables included are TSH and thyroxine at neonatal screening and 6 years later. Main outcomes are the risk of developing PH in childhood, linear growth, and development using Parents' Evaluation of Developmental Status (PEDS).

RESULTS

Out of 5040 normal-term newborns, 301 (6.0%, 95% CI 5.3-6.6%) have TSH ≥10 mU/l (TNH). Six years later, we re-examined 65 randomly selected children with TNH and 185 controls. In the TNH cohort, we found six out of 65 children (9.2%, 95% CI 1.4-17.0%) with PH (TSH ≥6.4 mU/l), and three out of 185 (1.6%, 95% CI 0.3-4.7%) among controls, relative risk 5.7 (95% CI 1.5-22.1), P=0.0114. TSH and developmental delay were found to be significantly higher in the TNH cohort (4.7±1.3 mU/l vs 2.1±0.5 mU/l, P<0.0001 and 15/65 (23%, 95% CI 12-34.1) vs 21/185 (11.3%, 95% CI 6.5-16.2) P=0.0348).

CONCLUSIONS

Newborns with TNH have a higher risk of developing PH in childhood, with repercussion on developmental status.

Impact of bilirubin-induced neurologic dysfunction on neurodevelopmental outcomes

Bilirubin-induced neurologic dysfunction (BIND) is the constellation of neurologic sequelae following milder degrees of neonatal hyperbilirubinemia than are associated with kernicterus. Clinically, BIND may manifest after the neonatal period as developmental delay, cognitive impairment, disordered executive function, and behavioral and psychiatric disorders. However, there is controversy regarding the relative contribution of neonatal hyperbilirubinemia versus other risk factors to the development of later neurodevelopmental disorders in children with BIND. In this review, we focus on the empiric data from the past 25 years regarding neurodevelopmental outcomes and BIND, including specific effects on developmental delay, cognition, speech and language development, executive function, and the neurobehavioral disorders, such as attention deficit/hyperactivity disorder and autism.

The clinical syndrome of bilirubin-induced neurologic dysfunction

Clinicians have hypothesized a spectrum of minor neurologic manifestations, consistent with neuroanatomical reports and collectively termed as a "syndrome of bilirubin-induced neurologic dysfunction (BIND)," which can occur in the absence of classical kernicterus. The current review builds on these initial reports with a focus on clinical signs and symptoms that are assessed by standardized tools and manifest from neonatal age to childhood. These clinical manifestations are characterized by the following domains: (i) neuromotor signs; (ii) muscle tone abnormalities; (iii) hyperexcitable neonatal reflexes; (iv) variety of neurobehavior manifestations; (v) speech and language abnormalities; and (vi) evolving array of central processing abnormalities, such as sensorineural audiology and visuomotor dysfunctions. Concerns remain that the most vulnerable infants are likely to acquire BIND, either because their exposure to bilirubin is not identified as severe enough to need treatment or is prolonged but slightly below current threshold levels for intervention. Knowing that a total serum/plasma bilirubin (TB) level is not the most precise indicator of neurotoxicity, the role of expanded biomarkers or a "bilirubin panel" has yet to be validated in prospective studies. Future studies that correlate early "toxic" bilirubin exposure to long-term academic potential of children are needed to explore new insights into bilirubin's effect on the structural and functional maturation of an infant's neural network topology.

Visuocortical bilirubin-induced neurological dysfunction

This review addresses the question whether elevated levels of total serum/plasma bilirubin (TB) cause measurable neurological effects, specifically to visuocortical functioning. Past research in the area of vision and its relation to jaundice has taken advantage of flash visual-evoked potentials (VEPs). Using a steady state VEP, we developed preliminary data suggesting that children who had jaundice with TB levels between 10 and 25mg/dL, but who did not have kernicterus, have measurable changes in visual function, when compared to control infants who did not have jaundice. This non-invasive test offers information about vision thresholds, signal amplitudes, and suprathreshold changes after brain exposure to bilirubin. Here, we review this novel tool, the steady state VEP, and data suggesting that neurological changes occur in infants with moderately elevated TB levels.

Direct antiglobulin titer strength and hyperbilirubinemia

BACKGROUND AND OBJECTIVES

We recently demonstrated that direct antiglobulin titer (DAT) positive, blood group A or B newborns born to group O mothers had a high incidence of hyperbilirubinemia, attributable to increased hemolysis. We reanalyzed our data asking whether increasing DAT strength plays a modulating role in the pathophysiology of the hemolysis and hyperbilirubinemia.

METHODS

Data from previously published DAT-positive, ABO-heterospecific neonates were analyzed for hyperbilirubinemia and hemolysis according to strength of DAT. DAT was measured by using a gel agglutination technique and reported as values ranging from DAT ± to DAT ++++. Hemolysis was evaluated by blood carboxyhemoglobin corrected for inspired, ambient CO (COHbc), and expressed as percent total hemoglobin (tHb). Hyperbilirubinemia was defined as any plasma total bilirubin value >95th percentile on the hour-specific nomogram.

RESULTS

Hyperbilirubinemia was more prevalent in those with DAT ++ readings (16 of 20, 80%) than those both DAT ± (37 of 87 [42.5%], relative risk: 1.88, 95% confidence interval: 1.35-2.61) and DAT + (32 of 56 [57.1%], relative risk: 1.40, 95% confidence interval: 1.02-1.92). COHbc values were higher for those with DAT ++ (1.45 ± 0.49% tHb [mean ± SD]) than those DAT ± (1.20 ± 0.37% tHb, P = .01) or DAT + (1.22 ± 0.37% tHb, P = .02).

CONCLUSIONS

DAT ++ readings were associated with a higher incidence of hyperbilirubinemia and higher COHbc values than DAT ± or DAT + counterparts. Increasing DAT strength may be a modulator of hemolysis and hyperbilirubinemia in ABO-heterospecific neonates. DAT strength, and not merely DAT presence or absence, should be taken into consideration in the management of ABO-heterospecific newborns.

Hyperbilirubinemia, hemolysis, and increased bilirubin neurotoxicity

Increased hemolysis in the presence of severe neonatal hyperbilirubinemia appears to augment the risk of bilirubin neurotoxicity. The mechanism of this intensifying effect is uncertain. In direct antiglobulin titer (DAT) positive, isoimmune hemolytic disease, the bilirubin threshold at which neurotoxicity occurs appears to be lower than in DAT-negative hyperbilirubinemia. In other hemolytic conditions, the hemolysis may simply facilitate the development of extremely high serum bilirubin levels. Whether the hemolytic process per se exerts an independent effect or whether a very rapid rise in serum bilirubin might lead to greater penetration of the blood-brain barrier is unclear. In this review, we survey the synergistic role of hemolysis associated with severe hyperbilirubinemia in the potentiation of bilirubin-induced neurotoxicity and suggest methods of identifying at-risk babies with increased hemolysis to allow for their increased surveillance.

Subtle bilirubin-induced neurodevelopmental dysfunction (BIND) in the term and late preterm infant: does it exist?

Subtle bilirubin-induced neurological dysfunction (BIND) is defined as disturbances in sensory and sensorimotor integration, central auditory processing, coordination, and muscle tone in the absence of the classical findings of kernicterus. This review is restricted to the (sensori)motor signs of BIND associated with unconjugated hyperbilirubinemia in term and late preterm neonates. The diagnosis of BIND at follow-up requires validated, age-specific techniques that are designed to identify these disturbances in infancy and later childhood. The (sensori)motor signs of BIND are compatible with the pathological substrate of unconjugated hyperbilirubinemia and its known effects on the brain.

Bilirubin-albumin binding, bilirubin/albumin ratios, and free bilirubin levels: where do we stand?

Treatment for unconjugated hyperbilirubinemia is predominantly based on one parameter, i.e., total serum bilirubin (TSB) levels. Yet, overt kernicterus has been reported in preterm infants at relatively low TSB levels, and it has been repeatedly shown that free unconjugated bilirubin (freeUCB) levels, or bilirubin/albumin (B/A) ratios for that matter, are more closely associated with bilirubin neurotoxicity. In this article, we review bilirubin-albumin binding, UCBfree levels, and B/A ratios in addition to TSB levels to individualize and optimize treatment especially in preterm infants. Methods to measure bilirubin-albumin binding or UCBfree are neither routinely performed in Western clinical laboratories nor incorporated in current management guidelines on unconjugated hyperbilirubinemia. For bilirubin-albumin binding, this seems justified because several of these methods have been challenged, and sufficiently powered prospective trials on the clinical benefits are lacking. Technological advances in the measurement of UCBfree may provide a convenient means for integrating UCBfree measurements into routine clinical management of jaundiced infants. A point-of-care method, as well as determination of UCBfree levels in various newborn populations, is desirable to learn more about variations in time and how various clinical pathophysiological conditions affect UCBfree levels. This will improve the estimation of approximate UCBfree levels associated with neurotoxicity. To delineate the role of UCBfree in the management of jaundiced (preterm) infants, trials are needed using UCBfree as treatment parameter. The additional use of the B/A ratio in jaundiced preterms has been evaluated in the Bilirubin Albumin Ratio Trial (BARTrial; Clinical Trials: ISRCTN74465643) but failed to demonstrate better neurodevelopmental outcome in preterm infants <32 weeks assigned to the study group. Awaiting a study in which infants are assigned to be managed solely on the basis of their B/A ratio (with TSB excluded ) versus TSB levels alone-and determining which group does better-the additional use of the B/A ratio in the management of hyperbilirubinemia in preterms is not advised. In conjunction with TSB levels, other parameters possibly allow for more accurate prediction of bilirubin toxicity. Yet, different methodologies for estimating these parameters exist, and sufficiently powered, prospective clinical trials supporting their clinical benefit, i.e., reduced bilirubin neurotoxicity when using these parameters, are lacking. Their use in addition to TSB needs to be prospectively evaluated, especially in preterm neonates, and preferentially in randomized clinical trials, which include specific risk factors and assessment of clinical relevant outcome measures for detecting those infants at risk of bilirubin toxicity.

Serum bilirubin and bilirubin/albumin ratio as predictors of bilirubin encephalopathy

BACKGROUND AND OBJECTIVE

Bilirubin/albumin ratio (B/A) may provide a better estimate of free bilirubin than total serum bilirubin (TSB), thus improving identification of newborns at risk for bilirubin encephalopathy. The objective of the study was to identify thresholds and compare specificities of TSB and B/A in detecting patients with acute and posttreatment auditory and neurologic impairment.

METHODS

A total of 193 term/near-term infants, admitted for severe jaundice to Cairo University Children's Hospital, were evaluated for neurologic status and auditory impairment (automated auditory brainstem response), both at admission and posttreatment by investigators blinded to laboratory results. The relationships of TSB and B/A to advancing stages of neurotoxicity were compared by using receiver operating characteristic curves.

RESULTS

TSB and B/A ranged from 17 to 61 mg/dL and 5.4 to 21.0 mg/g, respectively; 58 (30%) of 193 subjects developed acute bilirubin encephalopathy, leading to kernicterus in 35 infants (13 lethal). Auditory impairment was identified in 86 (49%) of 173 infants at admission and in 22 of 128 at follow-up. In the absence of clinical risk factors, no residual neurologic or hearing impairment occurred unless TSB exceeded 31 mg/dl. However, transient auditory impairment occurred at lower TSB and B/A (22.9 mg/dL and 5.7 mg/g, respectively). Intervention values of TSB and B/A set at high sensitivity to detect different stages of neurotoxicity had nearly the same specificity.

CONCLUSIONS

Both TSB and B/A are strong predictors of neurotoxicity, but B/A does not improve prediction over TSB alone. Threshold values detecting all affected patients (100% sensitivity) increase with advancing severity of neurotoxicity.

Visuocortical function in infants with a history of neonatal jaundice

PURPOSE

High concentrations of unconjugated bilirubin are neurotoxic and cause brain damage in newborn infants. However, the exact level of bilirubin that may be neurotoxic in a given infant is unknown. The aim of this study was to use a quantitative measure of neural activity, the swept parameter visual evoked potential (sVEP) to determine the relationship between neonatal bilirubin levels and visual responsivity several months later.

METHODS

We compared sVEP response functions over a wide range of contrast, spatial frequency, and Vernier offset sizes in 16 full-term infants with high bilirubin levels (>10 mg/dL) and 18 age-matched infants with no visible neonatal jaundice, all enrolled at 14 to 22 weeks of age. The group means of sVEP thresholds and suprathreshold response amplitudes were compared. The correlation between individual sVEP thresholds and bilirubin levels in jaundiced infants was studied.

RESULTS

Infants who had a history of neonatal jaundice showed lower response amplitudes (P < 0.05) and worse or immeasurable sVEP thresholds compared with control infants for all three measures (P < 0.05). Swept parameter visual evoked potential thresholds for Vernier offset were correlated with bilirubin level (P < 0.05), but spatial acuity and contrast sensitivity measures in the infants with neonatal jaundice were not (P > 0.05).

CONCLUSIONS

These results indicate that elevated neonatal bilirubin levels affect measures of visual function in infancy up to at least 14 to 22 weeks of postnatal age.

Incidence, etiology, and outcomes of hazardous hyperbilirubinemia in newborns

BACKGROUND AND OBJECTIVES

Total serum bilirubin (TSB) levels ≥ 30 mg/dL are rare but potentially hazardous. A better understanding of their incidence, causes, and outcomes could help inform preventive efforts.

METHODS

We identified infants born ≥ 35 weeks' gestational age from 1995-2011 in Kaiser Permanente Northern California (n = 525409) and examined the medical records of infants with a TSB ≥ 30 mg/dL to determine etiology and the occurrence of acute bilirubin encephalopathy. We reviewed inpatient and outpatient encounters through 2013 for evidence of sensorineural hearing loss (SNHL) or cerebral palsy (CP).

RESULTS

We identified 47 infants with TSB ≥ 30 mg/dL (8.6 per 100000 births). In 44 infants (94%), the hyperbilirubinemia occurred after the initial birth hospitalization. The etiology was not identified in 33 (70%). Glucose-6-phosphate dehydrogenase (G6PD) activity was measured in only 25 (53%) of whom 10 (40%) were deficient. Four children had acute bilirubin encephalopathy of whom 2 developed both CP and SNHL, and 1 developed isolated SNHL. These 3 infants all had G6PD deficiency and TSB >40 mg/dL. One additional 35-week infant with TSB 38.2 mg/dL had SNHL.

CONCLUSIONS

Hazardous (≥ 30 mg/dL) hyperbilirubinemia is a rare event. No etiology could be identified from the clinical record in most cases. G6PD deficiency was the leading cause of hazardous hyperbilirubinemia when an etiology was identified, but many were not tested. Chronic, bilirubin-induced neurotoxicity was uncommon and occurred only in the setting of additional risk factors and TSB values well over (>15 mg/dL) the American Academy of Pediatrics exchange transfusion thresholds.