Week 36 Q&A
You are asked to see a formerly premature male infant in the neonatal intensive care unit (NICU) for hypoglycemia.
The infant was born at 34 weeks’ gestational age, and did not require ventilation, although he was on oxygen for a short period of time. The infant, now 38 weeks’ corrected gestational age, has continued to struggle somewhat with feeding. He is rather large for his gestational age and continues to require a rather high rate of glucose infusion. You note that he does not have hepatomegaly. His most recent serum glucose level was 76 mg/dL, and he continues to receive a 12.5% dextrose concentration infusion. If the glucose infusion is stopped, serum glucose levels drift down rather quickly. The NICU providers have started an evaluation for hypoglycemia, and neither ketosis nor lactic acidosis has been seen.
What class of disorder is most likely the cause of this patient’s hypoglycemia?
A. Congenital hyperinsulinism.
B. Glycogen storage disease.
C. Ketotic hypoglycemia.
D. Organic aciduria.
E. Congenital disorder of glycosylation type 1a (CDG1a).
The correct answer is “A.” The fact that the infant is large for gestational age and has hypoketotic hypoglycemia in the absence of organomegaly is suggestive of hyperinsulinism. (See Figure 21–1.) Glycogen storage diseases generally present with organomegaly. Ketotic hypoglycemia is excluded by the text of the case study. (Were you reading carefully?) An organic aciduria is unlikely given the infant’s prominent hypoglycemia without prominent acidosis. Congenital disorders of glycosylation can cause hypoglycemia, although it is not prominently featured in CDG1a. Fatty acid oxidation disorders present after the neonatal period with hypoketotic hypoglycemia after fasting or during an illness.