Metabolism of bilirubin production↑: breakdown 1 g hemoglobin 34 mg bilirubin Adult 3.8 mg /kg.d Neonatal 8.5mg /kg.d cleaning v: Protein Y and Z l(in liver cell UDPGⅣ↓( glucuronyl transferase-葡萄糖醛酸转移酶) the enterohepatic circulation of bilirubinMetabolism of bilirubin production ： 1 g hemoglobin 34 mg bilirubin Adult 3.8 mg / kg.d， Neonatal 8.5mg / kg.d， cleaning : Protein Y and Z  (in liver cell ) UDPGT（glucuronyl transferase - 葡萄糖醛酸转移酶） the enterohepatic circulation of bilirubin breakdown