Neonatal Jaundice (Hyperbilirubinemia) 单补技大字同济等学西
Neonatal Jaundice (Hyperbilirubinemia)
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)
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)
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>129 mg/dl in the first four days of life are breast fed
Introduction ➢ ~60% of infants become clinically jaundiced in 1 st 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 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 barrier and results in neurotoxicity
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 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”:β- glucuronidase in the gut hydrolysis the conjugated bilirubin into unconjugated bilirubin. and reabsorbed into liver
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