Chapter 67: Hypoglycemia

I. PROBLEM

An infant has a low blood glucose level on bedside glucose testing. Hypoglycemia is the most common metabolic problem in neonates in the newborn nursery and neonatal intensive care unit (NICU). Neonatal hypoglycemia occurs most often (47%–52%) in at-risk infants who are small for gestational age (SGA) or large for gestational age (LGA), late preterm infants, or infants of diabetic mothers (IDM). It can occur in up to 10% of healthy term newborns. There is controversy surrounding neonatal hypoglycemia, including no absolute definition of hypoglycemia. Low glucose values may or may not result in clinical signs; the low value and duration of hypoglycemia that result in neurologic injury are unknown, and there are differing viewpoints from the American Academy of Pediatrics (AAP) and Pediatric Endocrine Society (PES) on hypoglycemia screening and guidelines. There is agreement that there are 2 forms of hypoglycemia in neonates: transitional hypoglycemia, which usually resolves within 48 hours after birth, and persistent hypoglycemia, which continues and can be pathologic. The AAP Committee on Fetus and Newborn states that the “absolute definition of hypoglycemia as a specific value or range cannot be given, as no evidence-based studies can define what clinically relevant neonatal hypoglycemia is.” Hypoglycemia definitions are based on treatment recommendation target threshold values:

1. American Academy of Pediatrics: In late preterm (34–36 6/7 weeks), term SGA infants, IDM, and LGA infants, hypoglycemia is defined as:

   1. Symptomatic infants at any age and asymptomatic infants from birth to 4 hours of age: <40 mg/dL.

   2. Asymptomatic infants (4–24 hours): <45 mg/dL.

2. Pediatric Endocrine Society. Defines hypoglycemia as “a plasma glucose concentration low enough to cause symptoms and signs of impaired brain function.”

   1. Infants: <60 mg/dL (normal threshold for neurogenic responses)

   2. Neonates with persistent hypoglycemia disorder:

      1. High-risk infants without a suspected congenital hypoglycemia disorder: <48 hours, <50 mg/dL; >48 hours, <60 mg/dL.

      2. Neonates with a suspected congenital hypoglycemia disorder: <70 mg/dL.

         This underscores the challenge in addressing the treatment for hypoglycemia. Because hypoglycemia can present as a neonatal emergency (seizures, loss of consciousness) and it is known to cause neurologic impairment (dose-dependent increased risk of poor executive function and visual motor function) per the Children with Hypoglycemia and Their Later Development (CHYLD) study, it is critical to recognize hypoglycemia and initiate treatment to avoid long-term neurologic impairment.

II. IMMEDIATE QUESTIONS

1. Was a serum sample sent to the laboratory stat? The blood glucose level should be repeated at the bedside, and a serum glucose should be sent to the laboratory stat. There are multiple ways to test for glucose (point-of-care blood glucose reagent test strips/point-of-care glucose meters, subcutaneous continuous glucose monitoring system [CGMS], and formal laboratory test). At present, there is no point-of-care method that is reliable and accurate enough to be used as the sole method for hypoglycemia screening.

   1. Point-of-care bedside reagent test strips/point-of-care glucose meter. Blood is obtained (heel stick or other method), and a drop ...