Overview
Definition:
Hypoglycemia in infants is defined as a blood glucose level below established thresholds for their postnatal age, which can be indicative of an underlying metabolic, endocrine, or infectious etiology
Critical sample collection is paramount for accurate diagnosis and timely management, preventing neurological sequelae.
Epidemiology:
Neonatal hypoglycemia affects 10-15% of all newborns, with higher incidence in preterm infants, infants of diabetic mothers, those with intrauterine growth restriction, and critically ill neonates
The incidence of persistent or severe hypoglycemia requiring investigation is lower.
Clinical Significance:
Untreated or prolonged hypoglycemia can lead to impaired brain development, seizures, developmental delay, and long-term neurocognitive deficits
Prompt and correct biochemical assessment, initiated by appropriate sample collection, guides therapeutic decisions and identifies underlying causes.
Clinical Presentation
Symptoms:
Jitteriness or tremors
Irritability or lethargy
Poor feeding
Vomiting
Cyanosis
Apnea
Hypotonia
Temperature instability
Seizures
Tachypnea.
Signs:
Often non-specific and may overlap with other neonatal conditions
Observe for signs of autonomic instability (pallor, sweating, tremor) and neurological dysfunction (lethargy, hypotonia, seizures).
Diagnostic Criteria:
Blood glucose below 2.6 mmol/L (47 mg/dL) in term infants in the first 3 days of life, and below 1.7 mmol/L (31 mg/dL) in preterm infants or at any time in the first week of life
Persistently low values (<2.2 mmol/L or 40 mg/dL) warrant further investigation.
Diagnostic Approach
History Taking:
Maternal history: diabetes, pre-eclampsia, infections, drug use
Pregnancy history: SGA, macrosomia, prolonged rupture of membranes, polyhydramnios
Birth history: birth trauma, perinatal asphyxia, prematurity
Infant history: feeding pattern, symptoms, duration, previous episodes
Family history of metabolic or endocrine disorders.
Physical Examination:
Assess gestational age
Look for dysmorphic features
Evaluate for signs of infection (fever, rash)
Assess hydration status
Perform a thorough neurological examination for signs of seizure activity, hypotonia, or altered consciousness
Check vital signs meticulously.
Investigations:
Point-of-care glucose monitoring using a glucometer is the initial step
If hypoglycemia is confirmed or suspected, immediate venous blood gas (VBG) or arterial blood gas (ABG) with glucose measurement is crucial
For further workup: serum lactate, ketones (urine or blood), insulin, C-peptide, cortisol, free fatty acids, amino acids, and acylcarnitine profiles are essential to differentiate etiologies
Urine metabolic screen and genetic testing may be indicated.
Differential Diagnosis:
Hyperinsulinism (e.g., congenital hyperinsulinism), endocrine deficiencies (hypopituitarism, adrenal insufficiency, hypothyroidism), metabolic disorders (glycogen storage diseases, fatty acid oxidation defects, amino acid disorders), intrauterine growth restriction, maternal diabetes, sepsis, polycythemia, transient hypoglycemia due to prematurity or perinatal stress.
Management
Initial Management:
Immediate feeding (oral or enteral) or intravenous (IV) glucose infusion
For symptomatic hypoglycemia, initial IV bolus of 10% dextrose at 2 mL/kg is recommended, followed by continuous infusion at 6-8 mg/kg/min, titrating to maintain blood glucose above 2.6 mmol/L (47 mg/dL).
Medical Management:
If persistent hypoglycemia despite adequate glucose infusion, consider pharmacologic agents
Glucagon (initial bolus, then infusion) can be used to stimulate hepatic glycogenolysis
Steroids may be considered for adrenal insufficiency
Diazoxide or octreotide may be used in cases of hyperinsulinism
Surgical intervention may be required for persistent hyperinsulinism.
Surgical Management:
Reserved for specific etiologies, primarily persistent congenital hyperinsulinism unresponsive to medical management
Options include partial pancreatectomy or genetic therapy.
Supportive Care:
Continuous glucose monitoring
Careful fluid and electrolyte balance
Nutritional support
Close monitoring for seizures and neurological status
Management of underlying cause
Multidisciplinary team approach involving neonatologists, pediatric endocrinologists, and metabolic specialists.
Complications
Early Complications:
Seizures
Neurological injury (e.g., hypoxic-ischemic encephalopathy, stroke)
Cardiac dysfunction
Renal vein thrombosis.
Late Complications:
Neurodevelopmental impairment (developmental delay, learning disabilities, attention deficit hyperactivity disorder)
Visual impairment
Hearing deficits.
Prevention Strategies:
Antenatal identification of high-risk pregnancies
Prompt recognition and initiation of treatment in newborns
Close monitoring of blood glucose in at-risk infants
Timely and accurate biochemical investigations to guide management.
Prognosis
Factors Affecting Prognosis:
Duration and severity of hypoglycemia
Presence and type of underlying etiology
Promptness of diagnosis and treatment
Neurological status at presentation
Responsiveness to treatment.
Outcomes:
Most infants with transient hypoglycemia recover fully with prompt treatment
Infants with persistent or severe hypoglycemia, or those with underlying genetic or metabolic disorders, have a higher risk of long-term neurological sequelae
Close follow-up is essential.
Follow Up:
Regular neurodevelopmental assessments
Audiometry and ophthalmology evaluations
Developmental pediatrics assessments up to school age
Ongoing monitoring for recurrence of hypoglycemia or progression of underlying disease.
Key Points
Exam Focus:
The definition of hypoglycemia in neonates (different thresholds for term vs
preterm)
Immediate steps in management including IV dextrose infusion rates
Key initial investigations (glucometer, VBG/ABG)
Recognition of symptomatic vs
asymptomatic hypoglycemia
Common causes of neonatal hypoglycemia.
Clinical Pearls:
Always obtain a serum glucose measurement from the same blood sample used for point-of-care testing to confirm findings
Consider a feeding intolerance or poor latch as early signs of hypoglycemia
Do not delay IV glucose if symptomatic, even while awaiting laboratory results
Differentiate between transient causes and persistent disorders requiring specialized workup.
Common Mistakes:
Relying solely on point-of-care glucometer readings without confirmatory lab tests
Delayed initiation of IV glucose in symptomatic infants
Inadequate glucose infusion rates leading to recurrent hypoglycemia
Failure to investigate the underlying cause of persistent hypoglycemia.