Neonatal Jaundice - Associates in Newborn Medicine

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neonatology neonatal jaundice Breastfeeding and Jaundice An important change in the United States population has been the dramatic increase in breastfeeding at hospital discharge from 30% in the 1960s to almost 70% today. In some hospitals, 85% or more of infants are breastfed. Multiple studies have found a strong association between breastfeeding and an increased incidence of neonatal hyperbilirubinemia. The jaundice associated with breastfeeding in the first 2 to 4 postnatal days has been called “breastfeeding jaundice” or “breastfeeding-associated jaundice”; that which appears later (onset at 4 to 7 d with prolonged jaundice) has been called “the human milk jaundice syndrome,” although there is considerable overlap between the two entities. Prolonged indirect-reacting hyperbilirubinemia (beyond age 2 to 3 wk) occurs in 20% to 30% of all breastfeeding infants and may persist for up to 3 months in some infants. Such infants have an increased incidence of Gilbert syndrome (diagnosed by UGT-1A1 genotyping from a peripheral blood sample). The jaundice associated with breastfeeding in the first few days after birth appears to be related to an increase in the enterohepatic circulation of bilirubin. This occurs in the first few days because until the milk has “come in,” breastfed infants receive fewer calories, and the decrease in caloric intake is an important stimulus to increasing the enterohepatic circulation. Pathologic Causes of Jaundice Table 2 lists the causes of pathologic indirect-reacting hyperbilirubinemia in the neonate. ABO Hemolytic Disease The use of Rh immunoglobin has dramatically decreased the incidence of Rh erythroblastosis fetalis, and hemolysis from ABO incompatibility is by far the most common cause of isoimmune hemolytic disease in newborns. In about 15% of pregnancies, an infant who has blood type A or B is carried by a mother who is type O. About one third of such infants have a positive direct antiglobulin test (DAT or Coombs test), indicating that they have anti-A or anti-B antibodies attached to the red cells. Of these infants, only 20% develop a peak TSB of more than 12.8 mg/dL (219 mcmol/L). Consequently, although ABO-incompatible, DAT-positive infants are about twice as likely as their compatible peers to have moderate hyperbilirubinemia (TSB 13 mg/dL [222.3 mcmol/ L]), severe jaundice (TSB 20 mg/dL [ [342 mcmol/ L]) in the infants is uncommon. Nevertheless, ABO hemolytic disease can cause severe hyperbilirubinemia and kernicterus. Table 2. Causes of Indirect Hyperbilirubinemia in Newborns Increased Production or Bilirubin Load on the Liver Hemolytic Disease ● Immune-mediated —Rh alloimmunization, ABO and other blood group incompatibilities ● Heritable —Red cell membrane defects: Hereditary spherocytosis, elliptocytosis, pyropoikilocytosis, stomatocytosis —Red cell enzyme deficiencies: Glucose-6- phosphate dehydrogenase deficiency, a pyruvate kinase deficiency, and other erythrocyte enzyme deficiencies —Hemoglobinopathies: Alpha thalassemia, beta thalassemia —Unstable hemoglobins: Congenital Heinz body hemolytic anemia Other Causes of Increased Production ● Sepsis a, b ● Disseminated intravascular coagulation ● Extravasation of blood: Hematomas; pulmonary, abdominal, cerebral, or other occult hemorrhage ● Polycythemia ● Macrosomia in infants of diabetic mothers Increased Enterohepatic Circulation of Bilirubin ● Breast milk jaundice ● Pyloric stenosis a ● Small or large bowel obstruction or ileus Decreased Clearance ● Prematurity ● Glucose-6-phosphate dehydrogenase deficiency Inborn Errors of Metabolism —Crigler-Najjar syndrome, types I and II —Gilbert syndrome —Galactosemia b —Tyrosinemia b —Hypermethioninemia b Metabolic —Hypothyroidism —Hypopituitarism b a Decreased clearance also part of pathogenesis. b Elevation of direct-reading bilirubin also occurs. Reprinted with permission from Maisels MJ. Jaundice. In: MacDonald MG, Seshia MMK, Mullett MD, eds. Neonatology: Pathophysiology and Management of the Newborn. Philadelphia, Pa: Lippincott Co; 2005:768–846. Diagnosing ABO Hemolytic Disease ABO hemolytic disease has a highly variable clinical presentation. Most affected infants present with a rapid Pediatrics in Review Vol.27 No.12 December 2006 445 Downloaded from http://pedsinreview.aappublications.org by J Michael Coleman on June 4, 2010
neonatology neonatal jaundice Table 3. Criteria for Diagnosing ABO Hemolytic Disease as the Cause of Neonatal Hyperbilirubinemia Mother group O, infant group A or B AND ● Positive DAT ● Jaundice appearing within 12 to 24 h after birth ● Microspherocytes on blood smear ● Negative DAT but homozygous for Gilbert syndrome Reprinted with permission from Maisels MJ. Jaundice. In: MacDonald MG, Seshia MMK, Mullett MD, eds. Neonatology: Pathophysiology and Management of the Newborn. Philadelphia, Pa: Lippincott Co; 2005:768–846. increase in TSB concentrations within the first 24 hours, but the TSB subsequently declines, in many infants, often without any intervention. ABO hemolytic disease is a relatively common cause of early hyperbilirubinemia (before the infant leaves the nursery), but it is a relatively rare cause of hyperbilirubinemia in infants who have been discharged and readmitted. The criteria for diagnosing ABO hemolytic disease as the cause of neonatal hyperbilirubinemia are listed in Table 3. Recently, it has been shown that DAT-negative, ABO-incompatible infants who also have Gilbert syndrome are at risk for hyperbilirubinemia. This may explain the occasional ABOincompatible infant who has a negative DAT and nevertheless develops early hyperbilirubinemia. Glucose-6-phosphate Dehydrogenase (G-6PD) Deficiency G-6PD deficiency is the most common and clinically significant red cell enzyme defect, affecting as many as 4,500,000 newborns worldwide each year. Although known for its prevalence in the populations of the Mediterranean, Middle East, Arabian Peninsula, southeast Asia, and Africa, G-6PD has been transformed by immigration and intermarriage into a global problem. Nevertheless, most pediatricians in the United States do not think of G-6PD deficiency when confronted with a jaundiced infant. This possibility should be considered, though, particularly when seeing African-American infants. Although African-American newborns, as a group, tend to have lower TSB concentrations than do caucasian newborns, G-6PD deficiency is found in 11% to 13% of African-American newborns. This translates to 32,000 to Table 4. Major Clinical Features of Acute Bilirubin Encephalopathy Initial Phase ● Slight stupor (“lethargic,” “sleepy”) ● Slight hypotonia, paucity of movement ● Poor sucking, slightly high-pitched cry Intermediate Phase ● Moderate stupor—irritable ● Tone variable, usually increased; some have retrocollis-opisthotonos ● Minimal feeding, high-pitched cry Advanced Phase ● Deep stupor to coma ● Tone usually increased; some have retrocollisopisthotonos ● No feeding, shrill cry Reprinted with permission from Maisels MJ. Jaundice. In: MacDonald MG, Seshia MMK, Mullett MD, eds. Neonatology: Pathophysiology and Management of the Newborn. Philadelphia, Pa: Lippincott Co; 2005:768–846. 39,000 African-American male G-6PD-deficient hemizygous newborns born annually in the United States. As many as 30% of infants in the United States who have kernicterus have been found to be G-6PD-deficient. The G-6PD gene is located on the X chromosome, and hemizygous males have the full enzyme deficiency, although female heterozygotes are also at risk for hyperbilirubinemia. G-6PD-deficient neonates have an increase in heme turnover, although overt evidence of hemolysis often is not present. In addition, affected infants have an impaired ability to conjugate bilirubin. Bilirubin Encephalopathy In the case described at the beginning of this article, the infant developed extreme hyperbilirubinemia and the classic signs of acute bilirubin encephalopathy (Table 4). He also developed the typical features of chronic bilirubin encephalopathy or kernicterus (Table 5). How Could This Have Been Prevented The infant in the case report had many of the factors that increase the risk of severe hyperbilirubinemia (Table 6). A key recommendation in the American Academy of Pediatrics (AAP) clinical practice guideline (Table 7) is that every infant be assessed for the risk of subsequent severe hyperbilirubinemia before discharge, particularly 446 Pediatrics in Review Vol.27 No.12 December 2006 Downloaded from http://pedsinreview.aappublications.org by J Michael Coleman on June 4, 2010
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