4.
acidosis, hypoalbuminemia
5. Immature of liver function
6.
lower ingestion (y, z protein); lower UDPGT activity
7. Increased “enterohepatic circulation”
the first four days of life are breast fed
Bilirubin Metabolism
derived from the catabolism of proteins that contain heme
the most important source is the breakdown of Hb from RBC native bilirubin is relatively insoluble in water at physiologic
pH, but it is very lipid soluble bilirubin circulates bound to albumin in equilibrium with its
unbound or "free" fraction the unbound fraction that readily crosses the blood-brain
infants 4. Jaundice declines gradually, reaching normal values 5. within 2 wks in term, and 3~4w (1~2m) in preterm 6. Causes no damage in term infants
3. The more frequently breast feeding occurs during the first few days, the lower are subsequent bili levels
4. can be prevented by teaching effective breast-feeding practices and support policies
Breast Milk Jaundice
Occurs infrequently (1%), peaks in 2~3wk, may persist at moderately high levels for 3-4 weeks before declining slowly
It is a diagnosis of exclusion In an otherwise well infant, it is considered a benign condition. If breast feeding stopped, the serum bilirubin usually falls The potential harms of stopping breast feeding would outweigh
新生儿黄疸（英文）
Introduction
All babies develop elevated serum bilirubin (SBR) levels, to a greater or lesser degree, in the first week of life. This is due to: increased production (accelerated RBC breakdown); decreased removal (liver enzyme insufficiency) Increased reabsorption (enterohepatic circulation).
barrier and results in neurotoxicity
Bilirubin Metabolism
Bilirubin is made more water-soluble in the liver by
conjugation with glucuronic acid to form "conjugated" or "direct-reacting" bilirubin, then cleared through the bile into the intestines and out through the feces. Phototherapy works by producing photoisomers of bilirubin that are more water soluble, and that can be cleared directly in bile or urine without conjugation in the liver. “enterohepatic circulation”: b-glucuronidase in the gut hydrolysis the conjugated bilirubin into unconjugated bilirubin, and reabsorbed into liver
Characteristics of Pathological Jaundice
Jaundice appears within 24 hrs of life Severe jaundice: SBR>12~15mg/dl, or >5mg/dl/day Sustained jaundice (term>2w, preterm>4w ) Recurrence of jaundice Increased serum conjugated bilirubin (>1.5~2mg/dl)
Introduction
~60% of infants become clinically jaundiced in 1st wk Bili levels peak at 3~5 days in full term infants ~1/6 of formula fed infants have bili levels over 12 ~1/3 of breast fed infants have bili levels over 12 Over 80% of all infants with bili levels>12.9 mg/dl in
congestive cardiac failure ("hydrops fetalis") The fetus is protected with placental removal of
bilirubin, following rapidly rising SBR after birth
ABO Incompatibility
any risks of a mild or moderate hyperbilirubinaemia Aetiology is unknown, some hormonal in the milk may acting
on the infant's hepatic metabolism, or enzyme (lipase) facilitating intestinal absorption of bilirubin.
Rhesus isoimmunisation
Rh antigen: C, D, E, c, d, e most common type is RhD [Rh (-) refers to D-] Rare in un-transfused 1st pregnancy In severe cases fetal anaemia develops, causing
Characteristics of Neonatal Bilirubin Metabolism
1. Increased bilirubin production
2.
8.8mg/kg daily vs 3.8mg/kg in adults
3. Insufficiency of bilirubin sportation
Breast-feeding Jaundice
1. increased bilirubin levels seen during the first week of life in infants who are breast fed
2. due to both caloric deprivation (mostly) and some fluid deprivation (a small part) during the first few days of life
8.
lower in gut bacteria; higher b-glucuronidase activity
“Physiological” Jaundice
1. Seen in 60% of term infants and over 80% of preterm 2. Serum values reaches maximum at 6mg/dl on 4~5d in 3. term and 10~12mg/dl on 5~7d in premature
Clinical Investigation: Kramer's Rule
Cephalocaudal Progression of Jaundice
Zone
1234 5
SBR (mmol/L) 100 150 200 250 >250
Clinical Investigation
Total SBR conjugated SBR full blood count - may reveal spherocytes or septic Group & Direct Coombs test –hemolytic jaundice high TSH & low T4 - suspect thyroid disease G6PD screen - male and appropriate ethnic group sepsis screen if indicated galactosaemia