Usefulness of the bilirubin/albumin ratio for predicting bilirubin-induced neurotoxicity in premature infants

Correlation Between Total Bilirubin, Total Bilirubin/Albumin Ratio with Disease Activity in Patients with Rheumatoid Arthritis

Purpose

Rheumatoid arthritis (RA) is a systemic inflammatory disorder with unknown etiology. Oxidative stress and immune imbalance play a critical role in the pathogenesis of rheumatoid arthritis. Bilirubin has recently been recognized as a potent antioxidant as well as an immunomodulatory agent of physiological importance. The aim of this study was to explore whether increased bilirubin concentrations are correlated with good clinical prognosis of rheumatoid arthritis.

Patients and Methods

In this cross-sectional study, we included 197 healthy individuals and 197 RA patients in the Affiliated Hospital of North Sichuan Medical College from October 2020 to February 2022. The latter were classified into three classes of disease activity according to DAS28-ESR: remission and low (DAS28-ESR<3.2), moderate (3.2≤DAS28-ESR≤5.1), and high (DAS28ESR>5.1). Based on the clinical and laboratory data, we evaluated the association of bilirubin levels with disease activity in RA using multivariable ordered logistic regression.

Results

The levels of total bilirubin and total bilirubin/albumin ratio were significantly lower (P < 0.001; P < 0.001) in RA patients compared with healthy controls. In RA patients, Spearman's rank correlation analysis revealed that bilirubin and total bilirubin/albumin ratio were negatively correlated with disease activity and inflammatory marker (C-reactive protein, erythrocyte sedimentation rate, Interleukin-6). In multivariable ordered logistic regression, higher total bilirubin (OR=0.77, 95% CI: 0.67-0.89, p<0.001) independently predicted lower disease activity.

Conclusion

Bilirubin levels remain associated with a reduction of disease activity, suggesting that bilirubin may be a protective factor for RA aggravation.

Cord blood albumin as a predictor of neonatal jaundice

Background and Aim

Bilirubin can have a toxic effect on the brain, so newborns must be carefully checked to identify those who may develop significant hyperbilirubinemia and bilirubin encephalopathy (kernicterus). The study aimed to determine if cord blood albumin could be utilized to predict the onset of significant newborn jaundice in healthy-term babies.

Patients and Methods

A cohort study was carried out in AL-Zahraa teaching hospital in AL-Najaf city during the period from January 1 to November 1, 2020. A randomized 100 full-term healthy neonates were enrolled. A blood sample was drawn by milking the cord and sent for serum albumin estimation. Patients were then followed up on the third and fifth days of life for total serum bilirubin (TSB).

Results

Out of 100 healthy-term neonates that were included in this study, 60 of them had low cord blood albumin (<2.8 g/dl), and 40 of them had normal cord blood albumin (≥2.8 g/dl) with an age range of 1-5 days. There is a statistically significant difference between low cord blood albumin and significant neonatal jaundice on the third day with a 5 times more risk of developing significant jaundice than neonates with normal cord blood albumin.

Conclusion

Cord blood albumin levels are sensitive to predicting subsequent neonatal jaundice in the healthy term newborn.

Current status of neonatal jaundice management in Japan

BACKGROUND

This nationwide survey aimed to determine the status of jaundice management in Japan.

METHODS

A questionnaire about bilirubin level measurements and neonatal jaundice treatment was sent to 330 institutions providing neonatal care. The responses were analyzed according to institution level.

RESULTS

Of 330 institutions, 172 responded (52.1% response rate). Total bilirubin levels were measured in the central laboratory using spectrophotometry at 134 institutions and a blood gas analyzer at 81 institutions. Unbound bilirubin (UB) levels were measured by 79 institutions, while transcutaneous bilirubin measurements were taken at 63 institutions. There was no association between institution level and UB or transcutaneous bilirubin measurement. For phototherapy criteria, the Murata-Imura criteria were adopted by 67 institutions, Nakamura criteria by 36, and Morioka criteria by 39. Light-emitting diodes (LED) were used by 160 institutions versus fluorescent lights by 31. When a blue LED was used, 119 institutions used the high mode. There is no standard for increasing light intensity. No association was found between institution level and phototherapy criteria. UB was measured in 14 of 63 institutions using the Murata-Imura criteria.

CONCLUSIONS

There is a large variation in the management and treatment of neonatal jaundice among institutes in Japan.

The development and validation of a predictive model for neonatal phototherapy outcome using admission indicators

Delayed exchange transfusion therapy (ETT) after phototherapy failure for newborns with severe hyperbilirubinemia could lead to serious complications such as bilirubin encephalopathy (BE). In this current manuscript we developed and validated a model using admission data for early prediction of phototherapy failure. We retrospectively examined the medical records of 292 newborns with severe hyperbilirubinemia as the training cohort and another 52 neonates as the validation cohort. Logistic regression modeling was employed to create a predictive model with seven significant admission indicators, i.e., age, past medical history, presence of hemolysis, hemoglobin, neutrophil proportion, albumin (ALB), and total serum bilirubin (TSB). To validate the model, two other models with conventional indicators were created, one incorporating the admission indicators and phototherapy failure outcome and the other using TSB decrease after phototherapy failure as a variable and phototherapy outcome as an outcome indicator. The area under the curve (AUC) of the predictive model was 0.958 [95% confidence interval (CI): 0.924-0.993] and 0.961 (95% CI: 0.914-1.000) in the training and validation cohorts, respectively. Compared with the conventional models, the new model had better predictive power and greater value for clinical decision-making by providing a possibly earlier and more accurate prediction of phototherapy failure. More rapid clinical decision-making and interventions may potentially minimize occurrence of serious complications of severe neonatal hyperbilirubinemia.

A deoxygenation-switch-based red-emitting fluorogenic light-up probe for the detection of highly toxic free bilirubin in human blood serum

Reaction-based chemical switches are attracting great interest due to their high selectivity, and their use has become a powerful technique for developing fluorogenic probes. Herein, a benzorhodol-derivative-attached N-oxide probe (DEBNox) has been designed as a new fluorogenic probe for the detection of the biologically toxic species bilirubin based on a deoxygenation switching mechanism. Upon reaction with added Fe³⁺, bilirubin produces Fe²⁺ ions in situ, which in turn promote a deoxygenation reaction with DEBNox to generate the corresponding high-red-fluorescence (λ_em: ∼623 nm) benzorhodol derivative (DEB). This type of Fe³⁺-mediated response helps the probe to act as a qualified turn on selective fluorescence sensor for bilirubin with a detection range as low as 33 nM. Moreover, the probe was successfully employed to detect free bilirubin in human blood serum specimens with acceptable accuracy and reliability. This DEBNox-based light-up strategy also facilitates the construction of reliable and highly sensitive assays based on a paper-based strategy, similar to pH-indicator paper, as is demonstrated here via bilirubin detection in real serum samples. These findings could be useful for developing powerful diagnostic tools for the detection of free bilirubin in the near further.

Can bilirubin/albumin ratio predict neurodevelopmental outcome in severe neonatal hyperbilirubinemia? A 3-month follow up study

Background

The risk of kernicterus and BIND may be in part determined by total serum bilirubin (TSB) and by the level of non-albumin bound free bilirubin, which can easily pass the blood–brain barrier. Free bilirubin (Bf) seems a more reliable predictor for bilirubin neurotoxicity. Bilirubin/albumin ratio (B/A) is considered a surrogate parameter for Bf and has been more useful than TSB. The aim of the study is to determine whether B/A ratio correlates with BIND in newborns with severe hyperbilirubinemia and if it can predict poor neurologic outcome at 3 months follow up.

Results

This prospective study included one hundred seventeen outborn neonates ≥ 35 weeks admitted in a tertiary care neonatal intensive care unit, between May and December 2012, with TSB ≥ 20 mg/dl or necessitating exchange transfusion. Total serum bilirubin and serum albumin were done on admission and bilirubin/albumin ratio was calculated. BIND score was calculated. At the age of 3 months, 112 neonates were followed up with a detailed neurological assessment. Babies who depicted any abnormal motor examination were subjected to brain stem auditory evoked response and MRI examination. Seven infants (6.2%) presented with kernicterus on follow up. BIND scores on admission, mean TSB, and bilirubin/albumin ratio was significantly higher in kernicteric infants compared with those having normal neurological outcome at 3 months of age (P 0.001). The lowest TSB level at which kernicterus occurred in our study was 31 mg/dl. Receiver operation characteristics analysis identified B/A ratio cut off value for predicting kernicterus of 9.6 with sensitivity of 100% and specificity of 91.4%, whereas TSB cut off value of 30 mg/dl showed sensitivity of 100% and specificity of 83%.

Conclusion

B/A ratio is a strong indicator for the risk of kernicterus. B/A is more specific than TSB and should be used in the early management of neonatal hyperbilirubinemia.

Neonatal Jaundice in Preterm Infants with Bilirubin Encephalopathy

INTRODUCTION

The aim of this study is to clarify bilirubin parameters and its treatment in preterm infants with bilirubin encephalopathy (pBE).

METHODS

We asked the responders to an earlier nationwide Japanese survey on pBE to provide additional information. pBE was diagnosed based on the criteria used in the nationwide survey. We collected data on serum total bilirubin (TB), direct bilirubin (DB), albumin, and unbound bilirubin (UB) levels during the first 8 weeks of life, and on phototherapy and exchange transfusion treatments.

RESULTS

We obtained clinical data from 75 patients with pBE from 58 hospitals (response rate of 59%), who were born between 2002 and 2016. The average peak TB level was 12.6 mg/dL (215 μmol/L), and the average age at peak attainment was 19.7 days after birth. Albumin level was <2.5 g/dL in 44 patients, and the peak DB level was ≥2 mg/dL (34.2 μmol/L) in 20 patients. The average peak bilirubin/albumin (B/A) (mg/g) ratio was 3.8 (molar ratio of 0.475), and the average age at peak attainment was 18.6 days. The average peak UB level was 0.67 μg/dL (11.5 nmol/L). The median duration of phototherapy was 6 days, and the median day of the last session was 12. The peak TB level occurred after the last day of phototherapy in 30 of the 61 patients available for comparison.

CONCLUSIONS

Most patients with pBE lacked marked elevations in serum TB levels and the B/A ratio, the peaks of which were sometimes delayed to >4 weeks after birth.

The role of bilirubin to albumin ratio as a predictor for mortality in critically ill patients without existing liver or biliary tract disease

Background:

Hyperbilirubinemia and hypoalbuminemia are frequently appeared and associated with poor prognosis in critically ill patients. We aim to evaluate the association between the bilirubin to albumin ratio and prognosis in intensive care unit (ICU) patients.

Methods:

This was a retrospective study of 731 patients who were admitted to the medical intensive care unit (MICU) at a tertiary-care center from July 2015 to September 2017. We analyzed the bilirubin to albumin ratio on admission to the MICU, including clinical characteristics and other examinations.

Results:

The overall 28-day survival of MICU patients was 69.1%. On univariate analysis, Acute Physiology and Chronic Health Evaluation (APACHE) II score (P<0.001), Sequential Organ Failure Assessment score (P<0.001), Simplified Acute Physiology Score II score (P<0.001), Creactive protein (P=0.015), and bilirubin/albumin ratio (P<0.001) were associated with mortality of ICU patients. The receiver operating characteristic curves for ICU patients mortality between bilirubin to albumin ratio and APACHE II score were not statistically significant (P=0.282). On multivariate analysis, higher APACHE II score (hazard ratio [HR], 1.05; 95% CI, 1.03 to 1.06; P<0.001) and bilirubin to albumin ratio (HR, 1.65; 95% CI, 1.23 to 2.20; P=0.001) were independently related to the ICU patient mortality.

Conclusions:

A higher bilirubin to albumin ratio was related to the unfavorable prognosis and mortality in critically ill patients.

Use of serum bilirubin/albumin ratio for early prediction of bilirubin induced neurological dysfunction

Background

Kernicterus or bilirubin encephalopathy is a preventable cause of handicap, still occurs in our country. The aim of the current study was to assess the role of bilirubin/albumin ratio in improving the morbidity of the cases with unconjugated hyperbilirubinemia and to estimate of the cutoff value for B/A ratio for prevention and early management of bilirubin-induced neurological dysfunction.

Results

The mean gestational age was 37.1 ± 2.11 weeks; the mean age of onset of jaundice was 2.36 ± 1.04 days; the mean level of total bilirubin was 26.14 ± 7.36 mg/dl. At chosen cutoff value of bilirubin albumin ratio (B/A) 6.68, sensitivity was 82% while specificity was 64% and accuracy was 95%.

Conclusion

Bilirubin encephalopathy still occurs in significant number in our country though it is a preventable cause of handicapping. TSB is a sensitive but not a specific indicator of ABE, B/A ratio is more specific indicator of the neurologic outcome and should be utilized in the decision of early intervention.

Early predictors of neonatal hyperbilirubinemia in full term newborn

BACKGROUND

Reliable predictive markers enabling physicians to identify which newborns will develop significant hyperbilirubinemia have become mandatory for prevention of severe hyperbilirunemia. We aimed at determining the critical cord serum bilirubin and albumin levels and bilirubin/albumin ratio early as reliable markers.

STUDY DESIGN

This prospective study included 175 full-term neonates. Measurement of cord bilirubin, albumin and bilirubin/albumin ratio was done to predict significant hyperbilirubinemia in healthy term newborns based on serum bilirubin measurements made within 5 days of life.

RESULTS

Most cases that developed significant neonatal hyperbilirubinemia (67.9%) had cord albumin level ≤ 2.8 gm/dl. Cord Bilirubin/albumin ratio cut off value > 0.61 had a good predictive value with a sensitivity of 100% and specificity of 88.4%, and cord serum albumin cut off value ≤ 3.0 mg/dl also had a good predictive value with a sensitivity of 85.7% and specificity of 67.3%. ROC curve analysis of cord total bilirubin demonstrated that a cut off value of ≥1.84 mg/dl had a good predictive value with a sensitivity of 100.0% and specificity of 87.1%.

CONCLUSION

Cord bilirubin/albumin ratio, serum bilirubin and albumin could be early predictors for neonatal hyperbilirubinemia.

Clinicopathological Spectrum of Bilirubin Encephalopathy/Kernicterus

Bilirubin encephalopathy/kernicterus is relatively rare, but continues to occur despite universal newborn screening. What is more interesting is the spectrum of clinical and even neuropathological findings that have been reported in the literature to be associated with bilirubin encephalopathy and kernicterus. In this review, the authors discuss the array of clinicopathological findings reported in the context of bilirubin encephalopathy and kernicterus, as well as the types of diagnostic testing used in patients suspected of having bilirubin encephalopathy or kernicterus. The authors aim to raise the awareness of these features among both pediatric neurologists and neuropathologists.

Unconjugated free bilirubin in preterm infants

BACKGROUND

Hyperbilirubinemia guidelines are based on total serum bilirubin (TSB), in combination with either gestational age (GA) or birth weight (BW), postnatal age and specific risk factors. However, TSB is a poor predictor of bilirubin-induced neurotoxicity (BIND). Free unconjugated bilirubin (UCBfree) and the UCBfree/TSB ratio are more directly related to BIND, but data on their postnatal courses are unknown.

AIMS

To characterize the postnatal courses of UCBfree and UCBfree/TSB ratio, and assess their relationships with clinical characteristics.

SUBJECTS

72 preterm infants≤32weeks GA, admitted to the University Medical Center Groningen, The Netherlands.

STUDY DESIGN

During the first postnatal week, bilirubin plasma parameters were analyzed and their relationship with clinical parameters was analyzed. Postnatal changes were analyzed using Generalized Estimating Equations. Data are expressed as medians [ranges].

RESULTS

Less than 10% of the cohort (GA: 29 [26-31] weeks; BW: 1165 [600-1975] g) showed hyperbilirubinemic risk factors. We observed a large variation in UCBfree (27 [1-197] nmol/L), that could partly be explained by postnatal age and gender, but not by other risk factors. Maximal UCBfree levels of 50 [13-197] nmol/L occurred at day 4 and were higher in males. In contrast to TSB, UCBfree/TSB ratios (0.19 [0.01-1.04]) were higher in infants with low GA/BW.

CONCLUSION

UCBfree levels vary considerably in preterm infants, despite a low incidence of hyperbilirubinemic risk factors and similar TSB-based phototherapy treatment. UCBfree could not be predicted by GA or BW, but UCBfree/TSB ratios are highest in the smallest preterms, while they have the lowest TSB levels.

Bilirubin levels and phototherapy use before and after neonatal red blood cell transfusions

BACKGROUND

Our previous retrospective study suggested that red blood cell (RBC) transfusion of preterm neonates can be associated with an increase in bilirubin, but this has not been tested prospectively.

STUDY DESIGN AND METHODS

We studied neonates before and after RBC transfusions, recording serial bilirubin levels and whether they qualified for phototherapy. Because lysed RBCs release plasma-free hemoglobin (Hb), a precursor to bilirubin, we also measured plasma free Hb and bilirubin from the donor blood.

RESULTS

We studied 50 transfusions given to 39 neonates. Gestation ages of transfused neonates, at birth, were 26 (24-29) weeks (median [interquartile range]); birthweights were 750 (620-1070) g. The study transfusion was given on Day of Life 9.9 (3.4-19.2). In 20% (10/50) phototherapy was being administered at the beginning of and during the transfusion. In these patients neither the 4- to 6- nor the 24- to 36-hour-posttransfusion bilirubin levels were significantly higher than before transfusion. However, in 30% of the others (12/40) phototherapy was started (or restarted) after the transfusion and 15% had a posttransfusion bilirubin increase of at least 2.5 mg/dL. These neonates received donor blood with a higher plasma-free Hb (p < 0.05).

CONCLUSIONS

Neonates commonly qualify for phototherapy after transfusion. A minority (15% in this series) have a posttransfusion bilirubin increase of at least 2.5 mg/dL. We speculate that neonates qualifying for a RBC transfusion, who are judged to be at high risk for bilirubin-induced neurotoxicity, might benefit from checking their serum bilirubin level after the transfusion and providing donor blood with low plasma-free Hb levels.

Hemolysis in Preterm Neonates

Hemolysis can be an important cause of hyperbilirubinemia in premature and term neonates. It can result from genetic abnormalities intrinsic to or factors exogenous to normal to red blood cells (RBCs). Hemolysis can lead to a relatively rapid increase in total serum/plasma bilirubin, hyperbilirubinemia that is somewhat slow to fall with phototherapy, or hyperbilirubinemia that is likely to rebound after phototherapy. Laboratory methods for diagnosing hemolysis are more difficult to apply, or less conclusive, in preterm infants. Transfusion of donor RBCs can present a bilirubin load that must be metabolized. Genetic causes can be identified by next-generation sequencing panels.

Disorders of bilirubin binding to albumin and bilirubin-induced neurologic dysfunction

Bilirubin-induced neurologic dysfunction (BIND) is a syndrome of subtle bilirubin neurotoxic disorders. The risk for developing BIND in newborns usually increases with elevated serum/plasma concentrations of unconjugated bilirubin. This risk is further increased by disorders of bilirubin binding to albumin, which includes a reduction in serum albumin concentrations or in the bilirubin-binding capacity and affinity of albumin, and the presence of displacing substances or infection. Serum unbound bilirubin (UB) concentration may be an ideal marker that reflects changes in bilirubin binding to albumin. Kernicterus, the chronic and with the most severe manifestations beyond BIND, is diagnosed by the presence of motor impairments with athetosis, abnormal magnetic resonance imaging, and/or brainstem auditory-evoked potential findings during infancy and childhood. Preterm infants sometimes have acute bilirubin encephalopathy without marked hyperbilirubinemia, such that bilirubin neurotoxicity occurs at bilirubin thresholds lower than usually associated with kernicterus. Disorders of bilirubin binding to albumin may be associated with the clinical signs of neurological injury associated with the lower bilirubin levels observed in preterm infants.

Bilirubin modulates acetylcholine receptors in rat superior cervical ganglionic neurons in a bidirectional manner

Autonomic dysfunction as a partial contributing factor to cardiovascular instability in jaundiced patients is often associated with increased serum bilirubin levels. Whether increased serum bilirubin levels could directly inhibit sympathetic ganglion transmission by blocking neuronal nicotinic acetylcholine receptors (nAChRs) remains to be elucidated. Conventional patch-clamp recordings were used to study the effect of bilirubin on nAChRs currents from enzymatically dissociated rat superior cervical ganglia (SCG) neurons. The results showed that low concnetrations (0.5 and 2 μM) of bilirubin enhanced the peak ACh-evoked currents, while high concentrations (3 to 5.5 µM) of bilirubin suppressed the currents with an IC₅₀ of 4 ± 0.5 μM. In addition, bilirubin decreased the extent of desensitization of nAChRs in a concentration-dependent manner. This inhibitory effect of bilirubin on nAChRs channel currents was non-competitive and voltage independent. Bilirubin partly improved the inhibitory effect of forskolin on ACh-induced currents without affecting the action of H-89. These data suggest that the dual effects of enhancement and suppression of bilirubin on nAChR function may be ascribed to the action mechanism of positive allosteric modulation and direct blockade. Thus, suppression of sympathetic ganglionic transmission through postganglionic nAChRs inhibition may partially contribute to the adverse cardiovascular effects in jaundiced patients.

The enigma of low bilirubin kernicterus in premature infants: why does it still occur, and is it preventable?

Low bilirubin kernicterus in preterm neonates, though rare, remains an unpredictable and refractory form of brain injury. Hypoalbuminemia, co-morbid CNS insult(s), infection, and inflammation are contributing causes that, in many cases, appear to interact in potentiating bilirubin neurotoxicity. Despite compulsive attention to serum bilirubin levels, and clinical and laboratory indices of neurotoxicity risk, low bilirubin kernicterus continues to be seen in contemporary NICUs. While efforts to refine and improve current treatment guidelines are certainly needed, such revision(s) will also have to take into account the risks and benefits of any intervention, including phototherapy.

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.

Problems with using total serum bilirubin as a criterion for phototherapy in extremely low-birthweight infants

BACKGROUND

Despite the early use of phototherapy and exchange transfusion in premature infants based on total serum bilirubin (TSB), the reemergence of kernicterus has been reported. The aim of this study was to assess the validity of using TSB as the criterion for phototherapy in extremely low-birthweight infants (ELBWI).

METHODS

We reviewed the medical charts of 43 ELBWI admitted to hospital between January 2009 and December 2010, and analyzed the relationship between TSB and unbound bilirubin (UB).

RESULTS

No infant underwent exchange transfusion or developed acute bilirubin encephalopathy. There was a significant correlation between TSB and UB measured immediately before phototherapy during the first 7 days of life (r = 0.657, P < 0.001), but none thereafter (r = 0.120, P = 0.213). Thirty-seven percent of infants who underwent phototherapy during the first 7 days of life had suprathreshold USB but subthreshold TSB, whereas this rose to 97% thereafter.

CONCLUSIONS

No correlation was observed between TSB and UB in ELBWI after the first 7 days of life, and almost all phototherapy sessions were initiated based on the UB criterion, even though TSB was below the accepted threshold. UB may be high if jaundice is evaluated solely on the basis of TSB.

The bilirubin albumin ratio in the management of hyperbilirubinemia in preterm infants to improve neurodevelopmental outcome: a randomized controlled trial--BARTrial

Background and Objective

High bilirubin/albumin (B/A) ratios increase the risk of bilirubin neurotoxicity. The B/A ratio may be a valuable measure, in addition to the total serum bilirubin (TSB), in the management of hyperbilirubinemia. We aimed to assess whether the additional use of B/A ratios in the management of hyperbilirubinemia in preterm infants improved neurodevelopmental outcome.

Methods

In a prospective, randomized controlled trial, 615 preterm infants of 32 weeks' gestation or less were randomly assigned to treatment based on either B/A ratio and TSB thresholds (consensus-based), whichever threshold was crossed first, or on the TSB thresholds only. The primary outcome was neurodevelopment at 18 to 24 months' corrected age as assessed with the Bayley Scales of Infant Development III by investigators unaware of treatment allocation. Secondary outcomes included complications of preterm birth and death.

Results

Composite motor (100±13 vs. 101±12) and cognitive (101±12 vs. 101±11) scores did not differ between the B/A ratio and TSB groups. Demographic characteristics, maximal TSB levels, B/A ratios, and other secondary outcomes were similar. The rates of death and/or severe neurodevelopmental impairment for the B/A ratio versus TSB groups were 15.4% versus 15.5% (P = 1.0) and 2.8% versus 1.4% (P = 0.62) for birth weights ≤1000 g and 1.8% versus 5.8% (P = 0.03) and 4.1% versus 2.0% (P = 0.26) for birth weights of >1000 g.

Conclusions

The additional use of B/A ratio in the management of hyperbilirubinemia in preterm infants did not improve their neurodevelopmental outcome.

Trial Registration

Controlled-Trials.com ISRCTN74465643

Low bilirubin kernicterus with sepsis and hypoalbuminaemia

A near-term female neonate with total serum bilirubin levels not exceeding the exchange transfusion level with hypoalbuminaemia developed abnormal movements while recovering from sepsis. Investigations showed an evidence of kernicterus on brain imaging and bilateral auditory neuropathic changes.

The evolving landscape of neurotoxicity by unconjugated bilirubin: role of glial cells and inflammation

Unconjugated hyperbilirubinemia is a common condition in the first week of postnatal life. Although generally harmless, some neonates may develop very high levels of unconjugated bilirubin (UCB), which may surpass the protective mechanisms of the brain in preventing UCB accumulation. In this case, both short-term and long-term neurodevelopmental disabilities, such as acute and chronic UCB encephalopathy, known as kernicterus, or more subtle alterations defined as bilirubin-induced neurological dysfunction (BIND) may be produced. There is a tremendous variability in babies' vulnerability toward UCB for reasons not yet explained, but preterm birth, sepsis, hypoxia, and hemolytic disease are comprised as risk factors. Therefore, UCB levels and neurological abnormalities are not strictly correlated. Even nowadays, the mechanisms of UCB neurotoxicity are still unclear, as are specific biomarkers, and little is known about lasting sequelae attributable to hyperbilirubinemia. On autopsy, UCB was shown to be within neurons, neuronal processes, and microglia, and to produce loss of neurons, demyelination, and gliosis. In isolated cell cultures, UCB was shown to impair neuronal arborization and to induce the release of pro-inflammatory cytokines from microglia and astrocytes. However, cell dependent sensitivity to UCB toxicity and the role of each nerve cell type remains not fully understood. This review provides a comprehensive insight into cell susceptibilities and molecular targets of UCB in neurons, astrocytes, and oligodendrocytes, and on phenotypic and functional responses of microglia to UCB. Interplay among glia elements and cross-talk with neurons, with a special emphasis in the UCB-induced immunostimulation, and the role of sepsis in BIND pathogenesis are highlighted. New and interesting data on the anti-inflammatory and antioxidant activities of different pharmacological agents are also presented, as novel and promising additional therapeutic approaches to BIND.

An evidence-based view on hyperbilirubinaemia

INTRODUCTION

We conducted a review of the evidence which contributes to the current care of jaundiced newborn infants.

METHODS

Literature was searched for reviews and randomized controlled trials (RCTs).

RESULTS

Six Cochrane reviews and eight other reviews and eighteen recent RCTs are discussed.

CONCLUSIONS

Many children still suffer life-long consequences of severe hyperbilirubinaemia, which could almost always have been prevented relatively easily. Up to date, guidelines summarizing the available evidence into unambiguous recommendations are needed to guide healthcare professionals in the prevention, diagnosis and treatment for infants with hyperbilirubinaemia.

Hyperbilirubinemia in infants with Gram-negative sepsis does not affect mortality

BACKGROUND

Sepsis is associated with an increased production of oxidant species and a decrease in endogenous antioxidant defenses. Mortality is high, especially when endotoxins are involved, e.g., in infants with Gram-negative sepsis. Yet, chronic as well as acute unconjugated hyperbilirubinemia has been shown to protect against endotoxin-induced shock in vivo in rats and in mice. We hypothesized that hyperbilirubinemia in infants with Gram-negative sepsis improves survival and/or mitigates the inflammatory response.

OBJECTIVE

To assess the relationships between serum bilirubin concentrations on the one hand, and leukocyte count, C-reactive protein and survival on the other hand, in infants with Gram-negative sepsis.

METHODS

Retrospectively, we retrieved clinical and biochemical data from infants less than 90 days of age with a blood culture-proven Gram-negative sepsis between January 1998 and December 2005.

RESULTS

We identified 92 infants with Gram-negative sepsis in the indicated period. Median gestational age was 29 (24-42) weeks. 22 Patients died. Preceding sepsis, median total serum bilirubin concentrations were below 150 μmol/L. Median concentrations of conjugated bilirubin concentrations increased (+63%, p<0.05), and median concentrations of unconjugated bilirubin decreased (-36%, p<0.05) in infants with Gram-negative sepsis. Median total bilirubin concentrations before and during sepsis were not significantly different between survivors and non-survivors. Changes in bilirubin concentrations were not significantly correlated with changes in either white blood cell count or C-reactive protein.

CONCLUSION

Present data do not support the concept that bilirubin positively affects survival or the inflammatory response in infants with Gram-negative sepsis.

Kernicterus in preterm infants

OBJECTIVE

We sought to clarify the features of kernicterus in preterm infants.

METHODS

The subjects of this study were 8 preterm infants with athetoid cerebral palsy whose gestational ages were < or =34 weeks. We retrospectively investigated clinical, laboratory, MRI, and brainstem auditory evoked potential (BAEP) findings.

RESULTS

Gestational age was < or =26 weeks in 6 of the 8 infants, and birth weight was <1000 g in 5 infants. Serious postnatal complications with systemic deterioration were observed in 3 infants. Total bilirubin levels were measured frequently in the majority of infants; peak values of >15 mg/dL were observed in 3 infants. No infant showed neurologic symptoms characteristic of classical acute bilirubin encephalopathy during the neonatal period. Dystonic posture and abnormal muscle tone were first recognized within 6 months' corrected age in all patients. During infancy, MRI was performed in 7 infants. Abnormal high-intensity areas were observed in the bilateral globi pallidi in all 7 infants. However, MRI during the neonatal period or after 1 year's corrected age showed no abnormal findings. BAEP measurements were abnormal in 7 of the 8 infants.

CONCLUSIONS

Preterm infants with athetotic cerebral palsy showed rather homogeneous features, similar to term infants with kernicterus, with marked hyperbilirubinemia. This combination of clinical, laboratory, neuroimaging, and neurophysiological data will contribute to the increased recognition of preterm infants with kernicterus.