A 4-day-old infant is seen for a routine newborn check; he has yellow skin from his face down to his chest. He is a full-term baby, had a normal vaginal delivery, weighed 3.180 kg at birth, and 3.100 kg at discharge. He is breastfeeding well, and stooling and voiding regularly. He is well-hydrated and active. Laboratory results reveal an indirect bilirubin of 12.2 mg/dL, and a direct bilirubin of 1.0 mg/dL.
What is the physiologic mechanism behind this jaundice?
A) An elevation of direct bilirubin due to decreased bilirubin production
B) The increased production of red blood cells
C) The increased conjugation of bilirubin by the liver
D) An elevation of indirect bilirubin due to increased bilirubin production
E) The decreased production of red blood cells
