The topic of hypoglycemia in neonates and children has generated significant debate of late, with the American Academy of Pediatrics (AAP) and the Pediatric Endocrine Society (PES) having advanced apparently conflicting guidelines.1,2 To avoid over-screening of healthy infants and children without discharging babies who may have glucose-regulation problems beyond the first days of life, the community pediatrician is perhaps best served by observing the AAP's approach for the first 48 hours, with increased vigilance consistent with the PES approach thereafter.3
The disconnect between the 2 societies' guidelines comes as little surprise, considering the paucity of evidence regarding clinically significant levels of neonatal hypoglycemia (NH) and the lack of consensus regarding a specific level or range to define hypoglycemia in the first 2 days of life.4
In reviewing NH studies to date, confounding factors such as variable definitions of hypoglycemia and lack of control groups make it impossible to define a specific plasma glucose (PG) concentration or duration that can predict permanent neurologic injury in high-risk infants.5-7 Although it is known that symptoms and long-term neurological damage occur within a range of low plasma glucose values of varying duration and severity,1 it is also critically important to remember that factors such as the presence of the alternative brain fuels beta-hydroxybutyrate (BOHB) and lactate, as well as hypoxia or ischemia, can affect whether brain injury will occur in conjunction with hypoglycemia.2
Hypoglycemia is defined as a glucose concentration low enough to cause signs or symptoms of impaired brain function (neuroglycopenia).8 Various authors have noted that the generally adopted plasma glucose concentration historically used to define NH for all infants, <47 mg/dL, lacks rigorous scientific justification.
Who, when, how?
To help determine which infants to screen, at what intervals, and what glucose levels to target during the first 48 hours of life, the AAP examined whether specific ranges of plasma glucose levels have been associated with neurodevelopmental harm in long-term follow-up studies (Table 11).3 Recommended values for intervention are somewhat arbitrary, the AAP concedes, but designed to provide a margin of safety above glucose concentrations associated with clinical signs.
The PES guidelines differ in that they expand the list of whom to screen and recommended that the target for treatment (not screening) in these at-risk babies is 50 mg/dL if being treated by feeding and 70 mg/dL if treated by intravenous (IV) glucose (Table 2).2