A 2-week-old girl is brought to the office because she looks "a bit yellow." She was born at 40 weeks gestation by normal spontaneous vaginal delivery to a mother whose blood type is AB+. Apgar scores were 9 (-1 color) and 9 (-1 color) at 1 and 5 minutes, respectively. Birth weight, length, and head circumference were at the 50th percentile. She was discharged home on the second day of life and has been breastfeeding every 2-3 hours for 15 minutes on each side. The infant has 6 wet diapers and 5-6 yellow seedy stools per day. She has regained her birth weight and has normal vital signs. Physical examination shows an active, crying infant with moist mucous membranes and jaundice of the face, neck, and chest. The remainder of the examination is normal. Total bilirubin is 10 mg/dL and direct bilirubin is 0.6 mg/dL.
Which of the following is the most likely cause of this infant's hyperbilirubinemia?

Question

A 2-week-old girl is brought to the office because she looks "a bit yellow."  She was born at 40 weeks gestation by normal spontaneous vaginal delivery to a mother whose blood type is AB+.  Apgar scores were 9 (-1 color) and 9 (-1 color) at 1 and 5 minutes, respectively.  Birth weight, length, and head circumference were at the 50th percentile.  She was discharged home on the second day of life and has been breastfeeding every 2-3 hours for 15 minutes on each side.  The infant has 6 wet diapers and 5-6 yellow seedy stools per day.  She has regained her birth weight and has normal vital signs.  Physical examination shows an active, crying infant with moist mucous membranes and jaundice of the face, neck, and chest.  The remainder of the examination is normal.  Total bilirubin is 10 mg/dL and direct bilirubin is 0.6 mg/dL. 
Which of the following is the most likely cause of this infant's hyperbilirubinemia?

Quizplus · Accepted Answer

Explanation: 11ec2b69_bf45_b63e_8f63_81201294615c_MD0005_00 Breast milk jaundice is a common cause of unconjugated hyperbilirubinemia in exclusively breast-fed infants that develops during the first 3-5 days of life and peaks by age 2 weeks. The etiology is thought to be due to high beta-glucuronidase activity in breast milk that deconjugates intestinal bilirubin and allows for increased intestinal absorption and enterohepatic circulation of bilirubin. Neonates are otherwise well-appearing, asymptomatic, and breastfeeding successfully. (Choice A) Alloimmune hemolytic disease of the newborn is typically caused by either ABO or Rh incompatibility between the fetus and mother. Risk factors include maternal blood type O and negative Rh status. Both ABO and Rh incompatibility are unlikely as the mother's blood type is AB+, indicating she has no antibodies against A, B, or Rh factor antigens. (Choice B) Biliary atresia presents as jaundice in the first 2 months of life due to conjugated hyperbilirubinemia (direct bilirubin >20% of total bilirubin) from progressive obstruction of the extrahepatic biliary tree. This infant has unconjugated hyperbilirubinemia, making this diagnosis unlikely. (Choice C) Breastfeeding failure jaundice occurs during the first week of life and is caused by lactation failure from inadequate milk supply, poor latch, or infrequent feeding. This decrease in oral intake results in decreased bilirubin elimination and increased intestinal absorption of bilirubin, thereby increasing serum bilirubin. This infant's age, normal weight, intake/output, and examination make this diagnosis unlikely. (Choice E) Gilbert syndrome typically manifests in adolescence as periodic asymptomatic jaundice from unconjugated hyperbilirubinemia. It rarely presents before puberty and is less common in girls, making this diagnosis less likely. Educational objective: Breast milk jaundice is a common cause of unconjugated hyperbilirubinemia that peaks at age 2 weeks in well-appearing and healthy neonates. In contrast, neonates with lactation failure typically present in the first week of life with jaundice, inadequate feeding, and dehydration. References: Management of hyperbilirubinemia in the newborn infant 35 or more weeks of gestation (http://www.ncbi.nlm.nih.gov/pubmed/15231951) Breastfeeding and jaundice. (http://www.ncbi.nlm.nih.gov/pubmed/11803412)

A 2-Week-Old Girl Is Brought to the Office Because She