Neonatal Nurse Practitioner Practice Exam

Physiologic jaundice in neonates is primarily due to what?

1. Defective conjugation

2. Decreased excretion of bilirubin

3. Increased hepatic uptake

4. Excessive breakdown of red blood cells

The correct answer is: Decreased excretion of bilirubin

Physiologic jaundice in neonates primarily arises from decreased excretion of bilirubin. In the first week after birth, it is common for neonates to exhibit elevated levels of bilirubin due to the immaturity of hepatic enzyme systems that are responsible for bilirubin conjugation and clearance. This immaturity can lead to an accumulation of unconjugated (indirect) bilirubin in the bloodstream, resulting in the yellow discoloration of the skin and sclera. During the neonatal period, the liver is not fully mature, and the pathways for metabolizing and excreting bilirubin are not yet fully developed. As a result, while the breakdown of red blood cells does increase after birth (due to the transition from fetal to neonatal circulation), the main issue leading to physiologic jaundice is the liver's reduced capacity to conjugate and excrete bilirubin effectively, rather than the breakdown of red blood cells itself. Understanding the physiological mechanisms underlying this condition is crucial for providers who manage infant health, as it can guide how to monitor and treat jaundice effectively in neonates.