Post on 10-Jan-2016
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The Metabolic Characteristics of Bilirubin in Newborns
Wu jinlinDepartment of Pediatrics
West China Second University Hospital Sichuan University
Baby on Phototherapy
Introduction of Neonatal Jaundice
Jaundice is quite common in neonatal period
[1] 60% of term infants and 80% of preterm infants
[2] Visible jaundice from sclera, mucosa and skin
Introduction of Neonatal Jaundice Can cause serious consequencesconsequences
[1] Actue phase
respiratory failure
bilirubin encephalopathy
neonatal death
[2] lifelong neurologic sequelae— kernicterus
cerebral palsy
epilepsy
mental retardation
auditory and visual disfunctions
Why jaundice is so prevalent
in neonatal period ???
The Metabolic Characteristics of
Bilirubin in Newborns
Normal Bilirubin Metabolism
Y&Z proteinUDPGT
β-glucuronidase
Albumin
shunt bilirubi
n
Enterohepatic Circulation
What’s the distinct metabolic characteristics of bilirubin in
newborns comparing with our adults?
1. Increased bilirubin production in newborns
2. Insufficient binding between bilirubin and albumin
3. Deficient bilirubin conjugation in the hepatocyte
4. Increased enterohepatic circulation of bilirubin
Neonatal Bilirubin Metabolism
5. Others
(1) Increased oxygen partial pressure1. Increased bilirubin production
PO2
PO2
RBC
RBC
bilirubin
[1] Life span of RBC
Preterm: ﹤70 days
Term: 80 days
Adult: 120 days
[2] Turnover rate of neonatal hemoglobin:
2 times faster than that of adults
(2) Short survival of neonatal erythrocyte1. Increased bilirubin production
(3) Over production of shunt bilirubin 1. Increased bilirubin production
heme
bone marrow precusor
shunt bilirubin
1. Increased bilirubin production in newborns
2.Insufficient binding between bilirubin and albumin
3. Deficient bilirubin conjugation in the hepatocyte
4. Increased enterohepatic circulation of bilirubin
Neonatal Bilirubin Metabolism
5. Others
2. Insufficient Binding between Bilirubin and Albumin low content of serum albumin GA albumin
bilirubin-albumin complex
different degree of acidosis at birth binding affinity
B
A
A
A
AB
AB
B
BB B
BB
B
A
B B
B
serum
1. Increased bilirubin production in newborns
2. Insufficient binding between bilirubin and albumin
3.Deficient bilirubin conjugation in the hepatocyte
4. Increased enterohepatic circulation of bilirubin
Neonatal Bilirubin Metabolism
5. Others
3. Deficient Bilirubin Conjugation in the Hepatocyte
UDPGTreaches the adult’s values 1 week after birth
Y carrier proteinincreases rapidly 5~10 days later
conjugation of bilirubin with glucuronic acid
1. Increased bilirubin production in newborns
2. Insufficient binding between bilirubin and albumin
3. Deficient bilirubin conjugation in the hepatocyte
4.Increased enterohepatic circulation of bilirubin
Neonatal Bilirubin Metabolism
5. Others
4. Increased Enterohepatic Circulation of Bilirubin
intestinal flora is not fully developed
abundant β-glucuronidase delayed excretion of meconium
1. Increased bilirubin production in newborns
2. Insufficient binding between bilirubin and albumin
3. Deficient bilirubin conjugation in the hepatocyte
4. Increased enterohepatic circulation of bilirubin
Neonatal Bilirubin Metabolism
5.Others
5. Others
dehydration
acidosis
intracranial hemorrhage
……
cephalohematoma
hunger
hypoxia
Summary
[1] Jaundice is much more frequent in neonates
[2] Pathogenesis : over-production of bilirubin
immature liver function