NPS Neonatal Physiology and Pathophysiology Flashcards

Why are preterm neonates at increased risk for hypoglycemia compared to term infants?

Answer: Limited glycogen stores and immature gluconeogenesis

Preterm neonates have limited hepatic glycogen stores, immature gluconeogenic enzymes, and high glucose utilization by the rapidly growing brain.

Patent ductus arteriosus (PDA) in a preterm neonate creates a left-to-right shunt. Which organ is MOST at risk from increased blood flow?

Answer: Lungs

Left-to-right PDA shunting increases pulmonary blood flow, causing pulmonary edema, worsening respiratory failure, and increased risk of BPD.

Retinopathy of prematurity (ROP) development is primarily driven by which pathophysiological mechanism?

Answer: Hyperoxia causing cessation of retinal vascularization followed by hypoxia-driven neovascularization

Hyperoxia stops normal retinal vessel growth; when oxygen is reduced, VEGF-driven pathological neovascularization occurs, which can cause retinal detachment.

A neonate has persistent metabolic acidosis with an elevated anion gap. Which condition should be suspected?

Answer: Inborn error of metabolism

An elevated anion gap metabolic acidosis in a neonate raises concern for inborn errors of metabolism (e.g., organic acidemias, maple syrup urine disease, or congenital lactic acidosis).

Which physiological change explains the normal 'physiological jaundice' seen in healthy term newborns at 2–5 days of life?

Answer: Breakdown of fetal RBCs releasing unconjugated bilirubin exceeding immature hepatic conjugation capacity

Physiological jaundice results from increased breakdown of short-lived fetal RBCs combined with immature hepatic UDP-glucuronosyltransferase activity and increased enterohepatic recirculation.

A newborn with trisomy 21 (Down syndrome) is found to have a large atrioventricular septal defect (AVSD). What is the most likely reason this lesion is particularly associated with trisomy 21?

Answer: Defects in endocardial cushion formation are common in trisomy 21

Trisomy 21 is associated with defective endocardial cushion development, leading to AVSD (affecting the AV valves and septal tissue) in up to 40% of affected individuals.