Review Question - QID 210966

A 2-week-old female infant presents to the pediatrician with new-onset seizures. She was born at home and the mother took folate and prenatal vitamins during her pregnancy. The patient's parents state that they noted odd rhythmic movements of her limbs and episodes where the patient is not responsive followed by a phase of somnolence. The patient was born to a G1P1 mother at 40 weeks gestation and is currently being breastfed. The patient has been tracking down from the 50th percentile for weight to the 10th percentile. Symptoms are typically noted after breastfeeding; however, they are not noticed when they feed the infant honey. Laboratory values are notable for a serum glucose of 38 mg/dL. Her temperature is 98.7°F (37°C), blood pressure is 90/52 mmHg, pulse is 121/min, respirations are 31/min, and oxygen saturation is 97% on room air. Physical exam is notable for hepatomegaly and the finding seen in Figure A. Which of the following is the most appropriate next step in management for this patient?