Monitor glucose levels in the infant. Hypoglycemia in the newborn is important and may go undetected
Monitor glucose levels in the infant. Hypoglycemia in the newborn is important and may go undetected: Excerpt from Avoiding Common Pediatric Errors
Author:
Heidi Herrera, MD and Nickie Niforatos, MD
What to Do - Gather Appropriate Data
Glucose is the major source of energy for tissue metabolism, particularly
in the brain, where lack of alternate energy stores makes glucose an essential substrate. If there is a lower than normal glucose level in the blood, so
that basic metabolic demands cannot be met, hypoglycemia results. A number of physiologic factors can leave the newborn particularly susceptible to
hypoglycemia. Infants have an increased brain-to-body weight ratio, with
a proportionately higher demand for glucose. In addition, newborns have
an immature counter-regulatory response, which limits the use of alternate
fuels, such as lactate and ketone bodies, in meeting basic metabolic requirements. Immediate consequences of hypoglycemia in the neonate include
poor outcomes, worsening sepsis, and asphyxia. In the longterm, neonatal
hypoglycemia may lead to impaired neurodevelopmental outcomes; some
studies suggest that recurrent severe hypoglycemia may result in neuronal
necrosis, contributing to impaired neurodevelopment.
Immediately after birth, the infant transitions from a maternal source of
glucosetotheirowninternalstores.Initially,themajorsourceofneonatalglucose is from hepatic glycogen, via glycogenolysis. Within the first few hours
of life, the neonate then develops the additional ability to maintain glucose
levels via gluconeogenesis. Decreased stores, increased demands, or inadequatemetabolicresponsesmaydisrupttheinfant'stransitiontoindependent
glycemic control. Table 14.1 provides the common neonatal risk factors that
may predispose the infant to hypoglycemia. Premature infants or small for
gestational age (SGA) infants have decreased glycogen stores, putting them
at risk for hypoglycemia. Septic infants, or infants with hypoxic-ischemic
injuries, may have increased demands for glucose. If the infant is unable
to meet these increased demands, hypoglycemia results. Infants of diabetic
mothers (IDMs) frequently have islet-cell hypertrophy and higher than normal insulin levels. When transitioning from maternal glucose stores to their
own stores, the insulin level may remain elevated, leading to hypoglycemia.
Table 14.1 Risk Factors
Prematurity
Small for gestational age
Intrauterine growth retardation
Asphyxia
Hypothermia
Sepsis
Infant of diabetic mother
Erythroblastosis fetalis
Exposure to β-agonist tocolytics
Familial hyperinsulinism
Inborn errors of metabolism
Endocrine disorders (pan-hypopituitarism, adrenal insufficiency, hypothyroidism, etc.)
Infants with mild hypoglycemia may remain asymptomatic. When
present, signs of hypoglycemia include jitteriness, poor suck, or unstable vital signs (Table 14.2). The spectrum of signs and symptoms of hypoglycemia are variable and nonspecific, which is why the clinician must have a high
index of suspicion for hypoglycemia to recognize, test, and treat it appropriately. Most nurseries have developed standard protocols to screen high-risk
infants. Although each infant's threshold for adequate glucose levels varies,
depending on their unique metabolic needs, commonly accepted values for
hypoglycemia in a term infant include blood values <2.0 mmol/L (<35
mg/dL) or plasma values <2.2 mmol/L (<40 mg/dL).
What to watch out for: If the initial history and physical exam rule out
common causes for hypoglycemia such as prematurity, SGA, or IDM, the
clinician must suspect sepsis.
What to watch out for: If hypoglycemia persists for >1 week, the clinician
must suspect more unusual but chronic causes, including hyperinsulinemia,
endocrine disorders, and inborn errors of metabolism.
Management
For asymptomatic infants whose hypoglycemia has been noted on an initial
screen,initial management is to provide enteral feeds (breast milk or formula).
Table1 4.2 Clinical Signs
Respiratory: Tachypnea; Apnea; Respiratory distress
Cardiovascular: Tachycardia; Bradycardia
Neurologic: Jitteriness; Lethargy; Weak suck; Temperature instability
These infants should continue to be monitored for 12 to 24 hours. If there
is a second episode of preprandial hypoglycemia, intravenous (IV) therapy
should be considered, even if the infant remains asymptomatic, recent literature suggests better neurodevelopment outcomes occur with better glycemic
control. For symptomatic infants or high-risk infants, immediate IV therapy
should be considered, as follows:
Bolus: 200 mg/kg dextrose (or 20 mL/kg of D10W),
THEN
Continuous: 5 to 8 mg/kg/min of glucose
If hypoglycemia recurs, repeat bolus and increase infusion by 15% to 20%
Once glucose levels have been stable for 12 to 24 hours, wean IV therapy
(reducetheinfusionrateby10%to20%eachtimebloodglucose>50mg/dL
(2.8 mmol/L))
What to watch out for: Dextrose concentrations >12.5% should ONLY be
administered via central catheter NOT by peripheral IV.
Suggested Reading
McGowan JE. Neonatal hypoglycemia. Pediatr Rev. 1999;20:e6–e15.
Pictures
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Book Source Details
- Book Title: Avoiding Common Pediatric Errors
- Author(s): Anthony D Slonim MD, DrPH; Lisa Marcucci MD
- Year of Publication: 2008
- Copyright Details: Avoiding Common Pediatric Errors, Copyright © 2008 Lippincott Williams & Wilkins.
More About Hyperglycemia
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Avoiding Common Pediatric Errors
Authors: Anthony D Slonim MD, DrPH; Lisa Marcucci MD
Publisher: Lippincott Williams & Wilkins
Copyright: 2008
ISBN: 0-7817-7489-6
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