LAUSR

A 4-day-old female newborn is transferred from an outside hospital for further evaluation and management of hypoglycemia. She had been born at 37 weeks’ gestation to a 23-year-old gravida 2, para 1 woman via spontaneous vaginal delivery. The prenatal history was unremarkable. She had a birthweight of 2,815 g (50th percentile) and length of 47 cm (40th percentile). She was initially discharged from the hospital on day 2 after birth. On day 4, she is brought back to the emergency department after 5 episodes of watery, nonbloody diarrhea and nonbloody, nonbilious emesis at home. In the emergency department, her vital signs are within the normal range for age. She is found to be hypoglycemic, with a blood glucose level of 31 mg/dL (1.7 mmol/L) for which she received a bolus of 10% dextrose in water. The repeat glucose level after the bolus is 84 mg/dL (4.6 mmol/L) and she is subsequently transferred to the NICU. On arrival at the NICU, her admission vital signs are within the normal range for age, and physical examination reveals a moderately dehydrated, nondysmorphic infant who is alert and fussy. She has jaundice to the umbilicus and a dermal melanocytosis spot near her sacrum. The remainder of her physical examination findings are within the range for age. Her blood glucose concentration is 53 mg/dL (2.9 mmol/L). Her admission blood gas measurements and complete blood cell counts are unremarkable. She is started on 10% dextrose water in addition to feedings of expressed breastmilk and supplemental infant formula as needed, at least every 3 hours. Blood and stool cultures are sent and prophylactic antibiotics initiated. Total and direct bilirubin concentrations are normal—9.6 mg/dL (164.2 μmol/L) and 0.3 mg/dL (5.1 μmol/L), respectively. Antibiotics are discontinued after the blood culture is found to be negative for 48 hours. Stool …