Nutrition, Fluids, and Metabolic Disorders Flashcards

Which enzyme deficiency causes phenylketonuria (PKU), detected on newborn screening?

Answer: Phenylalanine hydroxylase

PKU results from deficiency of phenylalanine hydroxylase, causing toxic phenylalanine accumulation that damages the developing brain if not detected and treated early.

A neonate receiving IV lipid infusion develops a triglyceride level of 350 mg/dL. What is the appropriate action?

Answer: Reduce or hold the lipid infusion until levels normalize

Hypertriglyceridemia indicates impaired lipid clearance; reducing or holding the lipid infusion prevents complications such as lipemia retinae and coagulopathy.

Human breast milk is recommended for premature infants primarily because it provides:

Answer: Immunologic protection, better gut tolerance, and reduced NEC risk

Breast milk provides secretory IgA, lactoferrin, and oligosaccharides that protect the immature gut, and is associated with significantly lower rates of NEC and sepsis.

Congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency causes a salt-wasting crisis in neonates due to deficiency of:

Answer: Aldosterone and cortisol

21-hydroxylase deficiency impairs synthesis of both aldosterone and cortisol, causing sodium wasting, hyperkalemia, and adrenal crisis in affected neonates.

What is the most appropriate initial fluid for treating severe hypernatremia (sodium >165 mEq/L) in a neonate?

Answer: Hypotonic fluid with gradual sodium correction over 48-72 hours

Rapid sodium correction in hypernatremia risks cerebral edema; gradual correction with hypotonic fluids at a rate of <0.5 mEq/L/hr reduces this risk.

A neonate has a serum glucose of 300 mg/dL on day 2 of TPN. What is the first step in management?

Answer: Reduce the dextrose concentration in TPN and recheck glucose

Reducing the dextrose concentration is the first step in managing neonatal hyperglycemia on TPN, as the glucose infusion rate may exceed the neonate's utilization capacity.