Neonatal jaundice bilirubin ( mostly not as bilirubin ) accumulate in the body caused by its complex causes, physiologic and pathologic points ; partially jaundice caused by central nervous system grams loss , resulting in bilirubin encephalopathy , it should strengthen the clinical observation of neonatal jaundice , find out why as soon as possible and timely treatment .
[ Neonatal metabolic characteristics of bilirubin ]
( A ) generating more neonatal bilirubin bilirubin generated daily about 8. 8mg/kg, while adults only 3. 8mg/kg. The reason: the low partial pressure of oxygen in the fetal environment , the greater the number of erythropoiesis , oxygen partial pressure to improve the environment after birth , the relative excess of red blood cells , damage resembles ; short half-life of fetal hemoglobin , red blood cell lifespan newborns than adults 20 to 40 days shorter cycle shortening bilirubin formation ; bilirubin produce more other sources , such as from the liver and other organs of a heme protein ( catalase , cytochrome P450 , etc. ) and the ineffective hematopoiesis in bone marrow ( a small amount of mature red blood cells are destroyed in the process ) is a precursor of bilirubin more .
Lack of capacity ( two ) running just delivered newborns bilirubin acidosis often have different degrees of impact on serum bilirubin and albumin joins, the number of albumin in preterm children is lower than the full-term children are so insufficient capacity of bilirubin transport .
(C ) the development of liver uptake of bilirubin is not necessary to improve ① Y newborn child within liver cells , low Z protein content of 5 to 10 days after the person reached levels ; ② formation of bilirubin functional difference , that liver cells urea aldehyde acid glycoside group II , glucose phosphate acyltransferase (UDPGT) and less than the content of low activity ( only 0 to 30% of normal ) , can not effectively lipophilic unconjugated bilirubin ( indirect bilirubin ) and glucuronic a water-soluble acid binding bilirubin ( direct bilirubin ) , this activity gradually to normal after a week ; ③ poor ability to excrete bilirubin , prone to cause cholestasis .
(D ) the characteristics of the enterohepatic circulation of newborn infants less intestinal bacteria can not be restored within a fecal intestinal bilirubin , urobilinogen ; and high intraluminal glucuronidase activity, bilirubin can combine Su hydrolysis of glucuronide and unconjugated bilirubin, which has been absorbed by the intestine and reach the liver through the portal .
Because of these characteristics , neonatal intake , combined with the ability excretion of bilirubin only 1 % to 2% of adults, and therefore prone to jaundice, especially when the newborn is hungry , hypoxia, delayed passage of meconium , dehydration, acid poisoning , cephalhematoma state jaundice or increased intracranial hemorrhage .
[ Classification ] neonatal jaundice
( A ) physiological jaundice due to the characteristics of neonatal bilirubin metabolism , about 50 % to 60% of full-term children , and> 80% of the preterm children jaundice in 2 to 3 days after birth , and reached a peak of 4 to 5 days ; General in good condition, full-term child in two weeks subsided , premature children can be extended to 3 to 4 weeks. Previous upper limit of the people currently in use physiological jaundice in newborns serum bilirubin , which in term children <205. 2μmol / L (12mg/dl) and preterm children <257μmol / L (15mg/dl), has been proposed objection , because even a small preterm children bilirubin <171μmol / L (10mg/dl), bilirubin encephalopathy may also occur . Children have been prescribed term foreign serum bilirubin <220 59μmol / L (12 9mg/dl.) Living jaundice boundaries ; domestic scholars found by monitoring the value of the upper limit of normal full-term children bilirubin physiological jaundice in 205 . between 2 ~ 256. 5μmol / L (12 ~ 15mg/dl), exceeding the original 205. 2μmol / L accounted for 31.3% ~ 48.5% , serum bilirubin in preterm children cap over 256.2 μmol / L were also accounted for 42.9% , so is through a national collaborative research diagnostic criteria proposed to revise our physiological jaundice .
(B ) jaundice often have the following characteristics : ① jaundice within 24 hours after birth ; ② severe jaundice, serum bilirubin > 205 2 ~ 256 5μmol / L, or rising daily over 85μmol / L (.. 5mg/dl); ③ jaundice long duration ( full-term children > 2 weeks , preterm children > 4 weeks ); ④ jaundice reappear ; ⑤ serum bilirubin > 26μmol / L (1 5mg/dl). . Of jaundice should actively look for the cause , the main cause of jaundice are:
( 1 ) neonatal hepatitis : Most of the fetus in the uterus caused by a viral infection , cytomegalovirus most common , the other for hepatitis B, rubella , herpes simplex, Coxsackie , EB virus, Listeria , Treponema pallidum , toxoplasmosis , etc. Infected via the placenta to the fetus through the birth canal or childbirth are infected. Usually 1-3 weeks after birth or later jaundice, light color , or gray stool when ill, dark urine, yellow , patients may have anorexia , vomiting, mild to moderate increases in liver .
( 2 ) neonatal sepsis .
2 . Noninfectious
( 1 ) hemolytic disease of the newborn .
( 2 ) biliary atresia of the disease has been confirmed that the majority is carried cholangitis , bile duct fibrosis and biliary atresia after birth due to the intrauterine infection caused by a virus ; If the wall is weak then form the common bile duct cysts. More than two weeks after birth and the beginning of significant jaundice was progressively increased ; fecal color from light yellow to white , the liver were increased , while hard and smooth ; liver change mainly to increased bilirubin . Three months after the gradual development of cirrhosis .
( 3 ) breast milk jaundice : about 1% of breastfed infants breast milk jaundice may occur , which is characterized by a non- hemolytic unconjugated bilirubin, often with overlapping physiological jaundice and persistent, serum bilirubin up to 342μmol / L (20mg/dl), a baby in good condition, drop jaundice in 4 to 12 weeks later, no cause can be found in other causes of jaundice . 3 days after stopping breastfeeding, such as jaundice declined to confirm the diagnosis. Now that this is because the breast- β- glucuronidase activity is too high, so that the bilirubin increased reabsorption in the intestine and cause jaundice ; some scholars believe that breastfeeding is to make such children within the intestinal bilirubin into urine, fecal urobilinogen caused by too little bacteria .
( 4 ) genetic disease : erythrocyte glucose 6 - phosphate dehydrogenase (G6PD) defect is more common in southern China , a higher incidence of kernicterus ; others such as pyruvate kinase deficiency of red blood cells , spherocytosis , galactosemia , α1 -antitrypsin deficiency, cystic fibrosis disease.
( 5 ) Drug Jaundice : as those caused by a vitamin K3, K4, novobiocin and other drugs.