A 10-hour-old boy is evaluated for jitteriness. The patient was born at 38 weeks gestation to a 36-year-old primigravid woman via cesarean delivery due to nonreassuring fetal heart tones. Pregnancy was complicated by maternal gestational diabetes. Birth weight was 4.5 kg (9 lb 14 oz). Apgar scores were 7 and 9 at 1 and 5 minutes, respectively. After birth, the patient had low blood glucose, which was treated appropriately. He has not yet had a bowel movement. The patient is afebrile with normal pulse and blood pressure. Oxygen saturation is 98% on room air. Examination shows a jittery neonate. Cardiopulmonary examination is unremarkable. There is no increased work of breathing, cyanosis, or tachypnea. The abdomen is soft, nontender, and nondistended. The remainder of the examination is unremarkable. Blood glucose is 65 mg/dL. Which of the following is the most appropriate next step in evaluation of this patient's symptoms?

Question

A 10-hour-old boy is evaluated for jitteriness.  The patient was born at 38 weeks gestation to a 36-year-old primigravid woman via cesarean delivery due to nonreassuring fetal heart tones.  Pregnancy was complicated by maternal gestational diabetes.  Birth weight was 4.5 kg (9 lb 14 oz).  Apgar scores were 7 and 9 at 1 and 5 minutes, respectively.  After birth, the patient had low blood glucose, which was treated appropriately.  He has not yet had a bowel movement.  The patient is afebrile with normal pulse and blood pressure.  Oxygen saturation is 98% on room air.  Examination shows a jittery neonate.  Cardiopulmonary examination is unremarkable.  There is no increased work of breathing, cyanosis, or tachypnea.  The abdomen is soft, nontender, and nondistended.  The remainder of the examination is unremarkable.  Blood glucose is 65 mg/dL.  Which of the following is the most appropriate next step in evaluation of this patient's symptoms?

Quizplus · Accepted Answer

11ec25c8_d70a_d187_bc81_5b670addb59b_MD0003_00 The most common cause of jitteriness in infants of diabetic mothers (IDMs) is hypoglycemia. However, this patient's serum glucose is now normal (≥40 mg/dL), making hypocalcemia the most likely cause. The pathophysiology of hypocalcemia in IDMs relates to maternal hypomagnesemia, which is caused by osmotic diuresis in the setting of poorly controlled gestational diabetes. Low fetal magnesium concentrations, which reflect maternal levels, lead to PTH suppression and low calcium levels in the neonate. Most newborns with hypocalcemia are asymptomatic; normalization of calcium levels usually occurs without intervention within days of birth, so routine screening is not required. However, symptomatic hypocalcemia can present with jitteriness, respiratory symptoms (eg, apnea, stridor from laryngospasm, wheezing from bronchospasm), and, if severe, seizures. Additional findings in IDMs may reflect consequences of excessive, maternally transferred glucose, such as increased fetal fat and glycogen storage leading to macrosomia in the infant (as seen here). If hypoglycemia in symptomatic IDMs is resolved, a serum calcium level should be obtained to confirm the diagnosis of hypocalcemia. Management typically involves correction of magnesium and then calcium. (Choice A) Abdominal x-ray may be indicated for delayed passage of meconium (age >48 hr), which can occur in IDMs due to a slight risk of small left colon syndrome (ie, transient dysmotility condition). This patient's abdominal examination is benign, and lack of stool is normal for his age. (Choice B) Arterial blood gas for assessment of oxygenation is indicated for respiratory distress syndrome, the risk of which is slightly increased in IDMs because fetal hyperinsulinemia can suppress surfactant production. However, patients typically have tachypnea, increased work of breathing (eg, retractions, grunting), and hypoxia, not seen here. (Choice C) Echocardiography is performed for suspected transient hypertrophic cardiomyopathy, an uncommon complication in IDMs due to glycogen deposition in the interventricular septum. This condition would not cause jitteriness, and a systolic murmur at the lower left sternal border due to left ventricular outflow tract obstruction would be expected. (Choice D) Preterm infants and those with macrosomia are at increased risk of neonatal hyperbilirubinemia, which can cause jitteriness if severe, but scleral icterus and marked jaundice would be present. Moreover, this condition does not typically occur on the first day of life. Educational objective: Metabolic complications of infants of diabetic mothers include hypoglycemia, hypocalcemia, and hypomagnesemia. Serum calcium level should be obtained for symptomatic neonates (eg, jitteriness), particularly if serum glucose is normal. References: Clinical approach to hypocalcemia in newborn period and infancy: who should be treated? (http://www.ncbi.nlm.nih.gov/pubmed/31320908)

A 10-Hour-Old Boy Is Evaluated for Jitteriness