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Hansen TWR, Wong RJ, Stevenson DK. Molecular Physiology and Pathophysiology of Bilirubin Handling by the Blood, Liver, Intestine, and Brain in the Newborn. Physiol Rev 2020; 100:1291-1346. [PMID: 32401177 DOI: 10.1152/physrev.00004.2019] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Bilirubin is the end product of heme catabolism formed during a process that involves oxidation-reduction reactions and conserves iron body stores. Unconjugated hyperbilirubinemia is common in newborn infants, but rare later in life. The basic physiology of bilirubin metabolism, such as production, transport, and excretion, has been well described. However, in the neonate, numerous variables related to nutrition, ethnicity, and genetic variants at several metabolic steps may be superimposed on the normal physiological hyperbilirubinemia that occurs in the first week of life and results in bilirubin levels that may be toxic to the brain. Bilirubin exists in several isomeric forms that differ in their polarities and is considered a physiologically important antioxidant. Here we review the chemistry of the bilirubin molecule and its metabolism in the body with a particular focus on the processes that impact the newborn infant, and how differences relative to older children and adults contribute to the risk of developing both acute and long-term neurological sequelae in the newborn infant. The final section deals with the interplay between the brain and bilirubin and its entry, clearance, and accumulation. We conclude with a discussion of the current state of knowledge regarding the mechanism(s) of bilirubin neurotoxicity.
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Affiliation(s)
- Thor W R Hansen
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - Ronald J Wong
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
| | - David K Stevenson
- Division of Paediatric and Adolescent Medicine, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Oslo, Norway; and Department of Pediatrics, Stanford University School of Medicine, Stanford, California
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Murli L, Thukral A, Sankar MJ, Vishnubhatla S, Deorari AK, Paul VK, Sakariah A, Dolma, Agarwal R. Reliability of transcutaneous bilirubinometry from shielded skin in neonates receiving phototherapy: a prospective cohort study. J Perinatol 2017; 37:182-187. [PMID: 27763628 DOI: 10.1038/jp.2016.189] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Revised: 07/26/2016] [Accepted: 08/15/2016] [Indexed: 11/09/2022]
Abstract
OBJECTIVE To determine the agreement between transcutaneous bilirubin (TcB) measured from shielded skin and serum total bilirubin (STB) in infants (34 to 41 weeks of gestation) with hyperbilirubinemia receiving phototherapy (PT). STUDY DESIGN In this prospective cohort study, we shielded a small area of skin on sternum using a commercial photo-opaque patch (BilEclipseTM, Philips Respironics, Murrysville, PA, USA). The TcB from the shielded skin (TcBs) and STB were measured at four time points-before initiation, 12 and 24 h during and once after (12 h) cessation of PT. TcB was measured using multiwavelength transcutaneous bilirubinometer (BiliChek, Philips Children's Medical Ventures, Monroeville, PA, USA). The STB was measured in triplicate by spectrophotometry (Apel BR 5100, APEL, Japan). Bland and Altman plots were drawn to determine agreement between the TcBs and STB. RESULTS The gestation and birth weight of enrolled neonates were 37.0 (1.0) weeks and 2750 (458) g, respectively. The age at initiation and duration of PT were 75 (27 to 312) and 25.3 (4.4) h, respectively. Bland and Altman plot showed poor agreement between TcBs and STB at all time points. The gradient (median, range) between TcBs and STB at 0, 12, 24 h and 12 h after cessation of PT were -0.2 (-4.9 to 3.5), 1.4 (-4.7 to 4.0), 1.5 (-3.8 to 9.4) and 2 (-2.9 to 5.8) mg dl-1. The proportions of TcBs values outside ±1.5 mg dl-1 of STB ranged from 47 to 64% at four time points. CONCLUSION TcBs does not appear to be reliable for estimating serum bilirubin in late preterm and term neonates receiving PT.
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Affiliation(s)
- L Murli
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - A Thukral
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - M J Sankar
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - S Vishnubhatla
- Department of Biostatistics, All India Institute of Medical Sciences, New Delhi, India
| | - A K Deorari
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - V K Paul
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - A Sakariah
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - Dolma
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
| | - R Agarwal
- Department of Pediatrics, Division of Neonatology, Newborn Health Knowledge Centre, WHO Collaborating Centre For Training and Research in Neonatal Care, ICMR Centre for Advanced Research in Newborn Health, All India Institute of Medical Sciences, New Delhi, India
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Abstract
Phototherapy is the main treatment for neonatal hyperbilirubinemia. In acute treatment of extreme hyperbilirubinemia, intensive phototherapy may have a role in 'detoxifying' the bilirubin molecule to more polar photoisomers, which should be less prone to crossing the blood-brain barrier, providing a 'brain-sparing' effect. This article reviews the biology of bilirubin isomers. Although there is evidence supporting the lower toxicity of bilirubin photoisomers, there are studies showing the opposite. There are methodologic weaknesses in most studies and better-designed experiments are needed. In an infant acutely threatened by bilirubin-induced brain damage, intensified phototherapy should be used expediently and aggressively.
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Affiliation(s)
- Thor Willy Ruud Hansen
- Division of Paediatric and Adolescent Medicine, Oslo University Hospital, Faculty of Medicine, Institute of Clinical Medicine, University of Oslo, Oslo, Norway.
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Roll EB, Christensen T. Formation of photoproducts and cytotoxicity of bilirubin irradiated with turquoise and blue phototherapy light. Acta Paediatr 2005; 94:1448-54. [PMID: 16263632 DOI: 10.1111/j.1651-2227.2005.tb01819.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
AIM To compare a new turquoise ("green") fluorescent phototherapy lamp (490 nm) with a conventional blue phototherapy lamp (450 nm) with respect to cytotoxicity and photochemical effects of bilirubin. METHODS Mouse lymphoma cells (L5178Y-R) in the presence of bilirubin solutions were exposed to phototherapy light. Occurrence of necrosis and apoptosis, reduction of mitotic index and inhibited cell growth was assayed by appropriate methods. The presence of bilirubin and its photoisomers was measured by high-pressure liquid chromatography analysis and absorption spectroscopy. RESULTS At constant and equal light irradiances, the cytotoxic effects in the presence of bilirubin bound to human serum albumin showed that the green lamp caused significantly less necrosis (n = 4, p < 0.05) and less inhibition of cell multiplication (n = 3, p < 0.05) than the blue lamp. A slightly lower apoptotic fraction, although not statistically significant, was observed in cells exposed to the blue lamp. Photo-oxidation of bilirubin was more prominent with blue light irradiation. The photoequilibria between geometric isomers of bilirubin were different for the two lamps; more geometric photoisomers were formed by blue irradiation (n = 6, p < 0.05). The amounts of the most water-soluble isomers (presumably mainly lumirubin) were rather similar for the two lamps. CONCLUSION The two lamps were similar in the formation of therapeutically relevant photoproducts, but the blue lamp showed potential in forming more photo-oxidation products and in causing more severe cellular damage in the presence of bilirubin.
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Okada H, Masuya K, Yasuda S, Okubo K, Kawada K, Kusaka T, Namba M, Nishida T, Imai T, Isobe K, Itoh S. Developmental changes in serum half-life of (EZ)-cyclobilirubin. Early Hum Dev 2005; 81:619-22. [PMID: 15975742 DOI: 10.1016/j.earlhumdev.2005.03.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2004] [Revised: 02/09/2005] [Accepted: 03/23/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Phototherapy has been a standard treatment for neonatal hyperbilirubinemia for more than 40 years, but it has remained sub-optimal. AIMS To clarify the developmental changes in parameters of (4E, 15Z)-cyclobilirubin ((EZ)-C) elimination in order to obtain basic data for establishing optimal phototherapy. STUDY DESIGN Blood samples were taken at regular intervals after stopping phototherapy, and bilirubin fractions were analyzed by high-performance liquid chromatography. SUBJECTS AND METHODS The subjects were 46 infants with hyperbilirubinemia who underwent phototherapy. The gestational age and birth weight of the subjects ranged from 25.0 to 41.0 weeks and from 656 to 3810 g, respectively, and the age at cessation of phototherapy was a median of 5 days. A kinetic model of (EZ)-C elimination was established, and the serum half-life of (EZ)-C was calculated on the basis of the determined model. Relationships of the half-life of (EZ)-C with birth weight and gestational age were investigated. RESULTS Serum (EZ)-C elimination followed a first-order kinetic model in 43 infants and a zero-order kinetic model in three extremely low birth weight infants. The half-life of (EZ)-C calculated on the basis of a first-order elimination model in serum ranged from 68 to 274 min and showed weak negative correlations with birth weight and gestational age. CONCLUSIONS Serum (EZ)-C excretion followed a first-order kinetic model in most of the neonates. The half-life of (EZ)-C becomes more prolonged in the very low birth weight infant and early gestational age.
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Affiliation(s)
- Hitoshi Okada
- Department of Pediatrics, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793, Japan.
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Abstract
AIM To investigate dermal bilirubin kinetics during phototherapy in the presence of neonatal indirect hyperbilirubinaemia. METHODS 33 neonates with non-haemolytic indirect hyperbilirubinaemia, who required phototherapy, were included in the study. Phototherapy modules containing four normal and four blue fluorescent lamps were used during the study. The transcutaneous bilirubin index (TcBI) was measured in an area of the forehead covered by a 2.5 cm diameter opaque patch and a nearby exposed site. The TcBI obtained from patched and unpatched areas and simultaneous serum bilirubin (SB) concentrations were measured before the start of phototherapy and after 6, 12, 18, 30, 42 and 66 h of phototherapy. RESULTS SB concentration and the TcBI from the unpatched area decreased significantly during the first 6 h of exposure, while the TcBI obtained from the patched area decreased significantly after 12 h. The TcBI from the unpatched area was consistently lower than that from the patched area during phototherapy. After the onset of phototherapy, there was a weak, non-significant correlation between SB concentrations and the TcBI from patched and unpatched areas. CONCLUSION Phototherapy was effective for both patched and unpatched areas, but the rate of decline was slower in patched areas, only becoming significant in the second 6 h of treatment. There was no significant correlation between the levels of SB and TcBI after the onset of phototherapy, and therefore the use of TcBI cannot be recommended as a surrogate measure of SB.
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Affiliation(s)
- H Ozkan
- Department of Pediatrics, Dokuz Eylül University Faculty of Medicine, Balçova, Izmir, Turkey
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Brito MA, Silva RM, Matos DC, da Silva AT, Brites DT. Alterations of erythrocyte morphology and lipid composition by hyperbilirubinemia. Clin Chim Acta 1996; 249:149-65. [PMID: 8737599 DOI: 10.1016/0009-8981(96)06285-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Morphology and membrane lipid composition of erythrocytes from neonates (jaundiced and healthy) and adults (before and after incubation with bilirubin) were studied. The morphological index, expressing the relative proportions of the different stages of cell distortion, and the membrane cholesterol, phospholipids and cholesterol/phospholipids molar ratio, were determined. In jaundiced neonates a significant increase in the morphological index (P < 0.01) was found. After incubation with bilirubin, adult erythrocytes also showed an increase in the morphological index (P < 0.01). Hemolysis occurred under these conditions, and the red cell ghosts obtained (vesicles) showed a rounded morphology. Higher cholesterol/phospholipid ratio and lower phospholipid content were found in jaundiced neonates compared with healthy babies (P < 0.05) and adults (P < 0.01), as well as in the cells (P < 0.05) and vesicles (P < 0.01) obtained after bilirubin incubation. Bilirubin cytotoxicity may occur in a stepwise manner: deposition of bilirubin in membrane produces echinocytosis, which is followed by disintegration of the lipid bilayer with loss of phospholipids from the membrane.
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Affiliation(s)
- M A Brito
- Centro de Metabolismos e Genética da Faculdade de Farmáeia da Universidade de Lisboa, Portugal
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