A 4-day-old newborn is brought to the office for a 2-day history of progressive jaundice. He was born at term following an uncomplicated vaginal delivery. The patient has been breastfed since birth. Vital signs are normal. Examination shows scleral icterus and jaundice from the face to the upper abdomen. Laboratory results are as follows: Which of the following is the most likely explanation for these findings?

Question

A 4-day-old newborn is brought to the office for a 2-day history of progressive jaundice.  He was born at term following an uncomplicated vaginal delivery.  The patient has been breastfed since birth.  Vital signs are normal.  Examination shows scleral icterus and jaundice from the face to the upper abdomen.  Laboratory results are as follows:  Which of the following is the most likely explanation for these findings?

Quizplus · Accepted Answer

11ec160b_3957_80f0_9249_8719326aaa4e_MD0001_00 This neonate most likely has benign neonatal hyperbilirubinemia, a physiologic condition characterized by an elevated indirect bilirubin level that peaks at age 2-5 days. The pathophysiology of benign neonatal hyperbilirubinemia includes the following: ↑ Bilirubin production: Fetal red blood cells (RBCs) are increased in number and have a shorter life span compared to RBCs in children and adults. Physiologic breakdown of these RBCs causes excess production of indirect bilirubin. ↓ Bilirubin clearance: Physiologically decreased levels of hepatic uridine diphosphogluconurate (UDP) glucuronosyltransferase in newborns results in decreased bilirubin conjugation and excretion into the bile. ↑ Enterohepatic circulation: Normally, bilirubin in the intestines is reduced by bacterial enzymes to allow for excretion through urine and stool. In the newborn, lack of bacterial enzymes due to relative gut sterility results in an increased bilirubin concentration remaining in the intestines. This excess bilirubin is deconjugated by intestinal beta-glucuronidase and then reabsorbed via the enterohepatic circulation (Choice B). Benign neonatal hyperbilirubinemia is typically asymptomatic except for scleral icterus and jaundice. The resolution of benign neonatal hyperbilirubinemia is expected by age 1-2 weeks as UDP glucuronosyltransferase activity and gut bacteria increase, allowing increased bilirubin clearance and excretion. (Choice A) Viral hepatitis (eg, hepatitis B or C) results in CD8⁺ T-lymphocyte-mediated hepatocellular injury and jaundice. However, vertical transmission of hepatitis viruses does not cause symptoms in the neonatal period. Moreover, once the patient is symptomatic, transaminases would be elevated. (Choice C) Glucose-6-phosphate dehydrogenase deficiency can present with jaundice and indirect hyperbilirubinemia in the early neonatal period. However, because hemolysis contributes to the pathophysiology of jaundice in this condition, the hematocrit would be decreased and the reticulocyte count would be elevated. (Choice E) Biliary atresia is characterized by fibrous obliteration of the extrahepatic biliary tree and typically presents with jaundice in the first 2 months of life. However, direct bilirubin is elevated due to biliary tract obstruction. In addition, patients often have acholic stools and dark urine. Educational objective: Benign neonatal hyperbilirubinemia presents with jaundice and elevated indirect bilirubin levels that peak at age 2-5 days. Pathophysiology includes impaired bilirubin clearance by the liver due to decreased hepatic UDP glucuronosyltransferase, an enzyme responsible for bilirubin conjugation. __________ References: Neonatal jaundice. (http://www.ncbi.nlm.nih.gov/pubmed/30422525)

A 4-Day-Old Newborn Is Brought to the Office for a 2-Day