A 5-day-old boy born to a 24-year-old woman is brought to the office for evaluation of poor feeding and vomiting. The pregnancy was uneventful and the mother had a normal delivery. Family history is noncontributory. The patient's temperature is 37.2 C (99 F), blood pressure is 60/30 mm Hg, pulse is 110/min, and respirations are 56/min. Physical examination reveals a lethargic newborn with exaggerated deep tendon reflexes and clonus. Further investigation reveals that the patient has an inherited condition that results in impaired transport of ornithine from the cytosol to the mitochondria. Nutritional restriction of which of the following substances can improve this patient's condition?

Question

A 5-day-old boy born to a 24-year-old woman is brought to the office for evaluation of poor feeding and vomiting.  The pregnancy was uneventful and the mother had a normal delivery.  Family history is noncontributory.  The patient's temperature is 37.2 C (99 F), blood pressure is 60/30 mm Hg, pulse is 110/min, and respirations are 56/min.  Physical examination reveals a lethargic newborn with exaggerated deep tendon reflexes and clonus.  Further investigation reveals that the patient has an inherited condition that results in impaired transport of ornithine from the cytosol to the mitochondria.  Nutritional restriction of which of the following substances can improve this patient's condition?

Quizplus · Accepted Answer

Eductional Objective: Ornithine transport into mitochondria is necessary for proper function of the urea cycle, which is the major disposal pathway for waste nitrogen generated by catabolism of amino acids.  Urea cycle defects typically cause neurological damage due to the accumulation of ammonia.  Protein restriction improves this condition by reducing the amount of amino acid turnover.

A 5-Day-Old Boy Born to a 24-Year-Old Woman Is Brought