Chapter 75: Management of Transient Hypoglycemia

BACKGROUND

Serum glucose levels (GLU) in the fetus are dependent on transplacental transfer of glucose from the mother and generally reflect maternal levels. Elevated maternal GLU can cause fetal hyperglycemia and increased insulin production by the fetal pancreas, resulting in fetal macrosomia. After separation from the placenta, newborn infants have to maintain their own GLU without maternal assistance. Thus, although usually euglycemic, the newborn could be either hyperglycemic or hypoglycemic depending on the maternal serum glucose and the infant’s ability for endocrine autoregulation.

EPIDEMIOLOGY

The exact incidence of transient neonatal hypoglycemia is unknown. Studies using continuous glucose monitoring have suggested that it is more common than previously believed, but the significance of this finding in asymptomatic, otherwise-well babies is unclear. Specific subgroups of neonates have been identified as having significantly increased risk of developing hypoglycemia:

• Small-for-gestational-age (SGA) infants

• Large-for-gestational-age (LGA) infants

• Infant of diabetic mother (IDM)

• Infant of gestational diabetic mother (IGDM)

• Septic infants

• Late preterm infants (LPTIs) born at 34⁺⁰ to 36⁺⁶ weeks’ gestation

• Postdate infants

CLINICAL FINDINGS

1. Maternal history suggestive of abnormal glucose status

   Diabetes mellitus

   Obesity

   Intravenous glucose administration

   Abnormal fetal growth

   Placental abnormalities (eg, too large/small, abruption)

   Fetal intolerance of labor (eg, abnormal tracing, meconium staining)

2. Neonatal findings suggestive of abnormal glucose homeostasis

   Intrauterine growth restriction/SGA

   Macrosomia/LGA

   Jitteriness

   Seizures

   Lethargy/poor feeding

   Apnea

   Unremarkable examination

LABORATORY WORKUP

Screening is recommended as follows only for at-risk infants:

1. IDM and LGA infants: screen for first 24 hours

2. LPTIs and SGA infants: screen for first 12 hours

3. Continue screening hypoglycemic infants until maintaining preprandial GLU 45 mg/dL or more for 2–3 feeding intervals

The definition of neonatal hypoglycemia has been debated, but most recently, the American Academy of Pediatrics (AAP) has defined it as follows:

• GLU less than 40 mg/dL and symptomatic

• GLU less than 25 mg/dL from birth to 4 hours of age after initial feeding

• GLU less than 35 mg/dL prior to subsequent feeding from 4 to 24 hours of age

A simplified algorithm for screening is shown in Figure 75-1.

TREATMENT

Enteral

Initial treatment is by enteral nutrition whenever possible if the baby is asymptomatic. See Figure 75-1 for a simplified treatment algorithm for asymptomatic neonates.