A 4-day-old boy is brought to the office due to a 2-day history of progressive jaundice. The patient was born at term following an uncomplicated pregnancy. He is formula fed. The patient and his mother are both blood group A, Rh-positive. Vital signs are normal. Examination shows scleral icterus and jaundice over the face and chest. Laboratory results are as follows: The patient is followed closely, and the jaundice resolves without intervention in 3 days. This patient's jaundice was most likely the result of which of the following changes in bilirubin metabolism compared to an adult?

Question

A 4-day-old boy is brought to the office due to a 2-day history of progressive jaundice. The patient was born at term following an uncomplicated pregnancy. He is formula fed. The patient and his mother are both blood group A, Rh-positive. Vital signs are normal. Examination shows scleral icterus and jaundice over the face and chest. Laboratory results are as follows:

The patient is followed closely, and the jaundice resolves without intervention in 3 days. This patient's jaundice was most likely the result of which of the following changes in bilirubin metabolism compared to an adult?

Quizplus · Accepted Answer

11ec160b_36d5_b8dc_9249_35fb3489a59b_MD0001_00 This newborn had elevated indirect bilirubin levels with jaundice that self-resolved in the first week of life, findings consistent with benign neonatal hyperbilirubinemia. Normally, unconjugated bilirubin is released into the bloodstream upon breakdown of red blood cells (RBCs) and taken up by the liver. Hepatic UDP glucuronosyltransferase then conjugates bilirubin, which is secreted into bile and excreted into the intestines. Bacterial enzymes in the intestines then reduce bilirubin to urobilinogen, allowing for excretion through the urine and stool. Benign neonatal hyperbilirubinemia is caused by several physiologic differences in bilirubin metabolism in newborns as compared to those in older children and adults. First, bilirubin production is increased due to increased breakdown of fetal RBCs, which are high in number (hematocrit up to 60%) and have a shorter life span (90 days as compared to 120 days in adults). Second, bilirubin conjugation is decreased due to physiologically lower levels of UDP glucuronosyltransferase in the immature neonatal liver. Finally, relative gut sterility in newborns results in decreased reduction of bilirubin to urobilinogen; instead, intestinal β-glucuronidase (which is synthesized both endogenously and by gut bacteria) deconjugates the bilirubin which allows it to be reabsorbed, therefore increasing enterohepatic circulation. Educational objective: Pathophysiology of benign neonatal hyperbilirubinemia involves increased bilirubin production and decreased bilirubin conjugation as well as increased enterohepatic circulation. Indirect hyperbilirubinemia and jaundice typically peak in the first few days of life and usually resolve without intervention. __________ References: Neonatal jaundice. (http://www.ncbi.nlm.nih.gov/pubmed/21920055) Neonatal jaundice. (http://www.ncbi.nlm.nih.gov/pubmed/30422525)

A 4-Day-Old Boy Is Brought to the Office Due to a 2-Day