A 1-hour-old boy in the newborn nursery has jitteriness and irritability. His serum glucose is 21 mg/dL. The infant was born by cesarean delivery for macrosomia and failure to progress. The infant has not yet breastfed as his mother is still recovering from surgery. He weighs 4.5 kg (9 lb 15 oz). His mother was prescribed insulin for gestational diabetes but has not taken it regularly. She also has a history of depression and intravenous drug use. She denies use of illicit drugs during the pregnancy and tested negative for HIV and hepatitis B and C in her third trimester. Which of the following factors is the most likely cause of this neonate's hypoglycemia?

Question

A 1-hour-old boy in the newborn nursery has jitteriness and irritability.  His serum glucose is 21 mg/dL.  The infant was born by cesarean delivery for macrosomia and failure to progress.  The infant has not yet breastfed as his mother is still recovering from surgery.  He weighs 4.5 kg (9 lb 15 oz).  His mother was prescribed insulin for gestational diabetes but has not taken it regularly.  She also has a history of depression and intravenous drug use.  She denies use of illicit drugs during the pregnancy and tested negative for HIV and hepatitis B and C in her third trimester.  Which of the following factors is the most likely cause of this neonate's hypoglycemia?

Quizplus · Accepted Answer

11ec160b_3ab7_86ea_9249_8b2e0425c0f5_MD0001_00 Poor glucose control before or during pregnancy is associated with adverse effects on the fetus and newborn. Macrosomia (>4 kg [8 lb 14 oz]) is a common finding in infants of diabetic mothers. Poor maternal glucose control leads to excessive transplacental glucose transfer to the fetus, which stimulates fetal insulin production. Chronic stimulation of the fetal beta cells leads to beta cell hyperplasia and hyperinsulinism. Elevated insulin levels contribute to increased fat deposition and enhanced fetal growth, resulting in macrosomia. After delivery, the infant experiences a sudden interruption in transplacental glucose transfer, but the hyperinsulinism remains due to the beta cell hyperplasia. This can result in rapid development of profound hypoglycemia, and affected infants require frequent feedings or parenteral glucose to prevent hypoglycemia and subsequent neurologic injury. In most cases, supportive care is all that is required; the beta cell hyperplasia will resolve over time. (Choice B) Glycogen storage diseases are caused by enzymatic defects that impair glycogenolysis. Types that affect the liver typically present with hypoglycemia and lactic acidosis. Symptoms usually do not start until age 3-4 months, when glycogenolysis is needed to sustain blood glucose during longer feeding intervals. (Choice C) Most infants with hypothyroidism are asymptomatic. Clinical manifestations include lethargy, irritability, and poor feeding and growth. Hypoglycemia shortly after delivery is not a common finding in neonatal hypothyroidism. (Choice D) Insulin-like growth factor 2 (IGF-2) is important in fetal development. However, IGF levels are not increased in infants of diabetic mothers. (Choice E) Maternal insulin is not transferred to the fetus but rather is catabolized by the placenta. Educational objective: Maternal hyperglycemia causes increased transplacental glucose delivery to the infant, fetal hyperglycemia, and, ultimately, beta cell hyperplasia. The resulting hyperinsulinemia caused by islet cell hyperplasia is associated with fetal macrosomia and hypoglycemia after delivery.

A 1-Hour-Old Boy in the Newborn Nursery Has Jitteriness and Irritability