What determines the need for blood glucose labs in newborns?

Determining the Need for Blood Glucose Labs in Newborns

Blood glucose monitoring in newborns should be determined primarily by the presence of specific risk factors, with the most common being maternal diabetes (31.5%), large for gestational age (26.2%), small for gestational age (24.5%), and prematurity (13.2%). 1

Primary Risk Factors Requiring Blood Glucose Screening

• Infants of mothers with diabetes are at significant risk for hypoglycemia and require monitoring 2
• Preterm infants (born before 37 weeks' gestation) require blood glucose screening 2
• Small for gestational age infants (below the 10th percentile) need monitoring 2
• Large for gestational age infants (above the 90th percentile) should be screened 2
• Low birth weight infants (<2500g) require glucose monitoring 2
• High birth weight infants (>4500g) need blood glucose screening 2
• Post-term infants (born after 42 weeks' gestation) should be monitored 2
• Infants with perinatal asphyxia require glucose monitoring due to increased risk 3

Screening Prevalence and Timing

• Approximately 26.3% of otherwise healthy newborns meet criteria for hypoglycemia screening based on risk factors 1
• The proportion of infants eligible for screening has increased from 25.6% in 2004 to 28.5% in 2018, primarily due to increasing rates of maternal diabetes 1
• Maternal diabetes as a risk factor for screening eligibility has increased significantly from 20.1% in 2004 to 41.7% in 2018 1
• Ethnic differences exist in screening eligibility, with infants of Indian (37.8%) and Pacific (32.1%) mothers more likely to require screening compared to infants of European mothers (22.3%) 1

Diagnostic Thresholds and Measurement Considerations

• Hypoglycemia in newborns should be defined as blood glucose below 2.5 mmol/L (45 mg/dL), with specific intervention thresholds based on clinical presentation and risk factors 3
• Blood glucose measurements should preferably be performed using blood gas analyzers with glucose modules, as they provide the best combination of quick results and accuracy 1
• The accuracy of handheld blood glucose meters in newborns is concerning due to interference from high hemoglobin and bilirubin levels 1, 4
• A single measurement of blood glucose <1 mmol/L (18 mg/dL) should prompt immediate intervention 3
• Blood glucose <2 mmol/L (36 mg/dL) that remains below this value at the next measurement requires intervention 3
• A single measurement of <2.5 mmol/L (45 mg/dL) in a newborn with abnormal clinical signs requires intervention 3

Clinical Implications and Management

• Up to 50% of at-risk infants develop low blood glucose concentrations, making screening crucial 2
• Severe and prolonged hypoglycemia is associated with neurological injury and long-term neurodevelopmental sequelae 2, 5
• Hypoglycemia is often asymptomatic or presents with nonspecific clinical signs, making screening of at-risk infants essential 2
• Supervised breastfeeding may be an initial treatment option for asymptomatic hypoglycemia 6
• Symptomatic hypoglycemia should always be treated with continuous infusion of parenteral dextrose 6
• Neonates requiring dextrose infusion rates above 12 mg/kg/min should be investigated for a definite cause of hypoglycemia 6
• Oral glucose gel is effective for prevention and treatment of neonatal hypoglycemia in at-risk newborns 7

Common Pitfalls and Caveats

• There is lack of consensus between guidelines on the exact definition of at-risk infants 2
• Point-of-care glucometers may be inaccurate in detecting neonatal hypoglycemia, with varying performance among different devices 2, 4
• Screening practices may disrupt establishment of breastfeeding 2
• Rapid rises in glucose concentrations following treatment may be associated with poorer neurodevelopmental outcomes 2
• Glucose disturbances in preterm infants are common and mostly asymptomatic, requiring careful monitoring especially in late preterm infants 8
• Female gender increases the chance of developing hypoglycemia by three times in preterm infants 8
• Decreasing gestational age, sepsis, respiratory distress syndrome, and mechanical ventilation significantly increase the risk of hyperglycemia 8