Understanding Neonatal Hypoglycemia

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When caring for neonates, relying on your assessment and the whole clinical picture is crucial. Neonates can decline quickly with potentially only subtle indicators before becoming unstable. Neonatal hypoglycemia can result in seizures, heart failure, and brain damage when left untreated (5). Awareness of hypoglycemic identifiers including potential risk factors, signs and symptoms, or trends from baseline will help assist you to prompt recognition. 

Introduction 

When caring for newborns in their first hours of life, there’s a multitude of events happening. Parents, siblings, and visitors are bonding with this new addition to the family. The first feeding, touching, and gazing is all happening. Newborns let out that initial cry, that first yawn, first stretch, or finger grasp that we all find comfort in. While all of these beautiful moments are happening, newborns are making their transition to extra-uterine life through multiple organ systems. Some of these transitions don’t always go as planned. One of the most frequently occurring problems with newborns within 48 hours of life is a metabolic one, known as neonatal hypoglycemia (1). While hypoglycemia is a common occurrence in newborns, defining parameters with glucose serum levels for recognition is a bit varied, leading to difficult clinical guidance.

Risk Factors & Causes 

While beginning to understand neonatal hypoglycemia, understanding the potential risk factors and causes of this diagnosis will give you an upper hand in the diagnosing and overall treatment of hypoglycemia in neonates. At the time of delivery and when the cord is cut, newborns take over their own body homeostatic functioning.  

Risk Factors (2)

Preterm 

• Newborns less than 37 weeks gestation at delivery 
• The majority of glycogen is stored during the end of the third trimester, leaving these newborns with a shortage of glycogen stores that are rapidly depleted after birth, especially if any other complications are causing what glycogen stores these newborns do have to deplete quickly (2).
  

Small for Gestational Age (SGA) 

• Weight below the 10th percentile (1) 

Large for Festational Age (LGA) (2) 

• Weight above the 90th percentile (1) 
• Newborns born with LGA have more overall body fat, creating more use of glycogen stores to support their large body mass.  

Infants of Diabetic Mothers (IDM) (2) 

• Since newborns are dependent on the placenta and maternal body functions to provide glucose during pregnancy, if the maternal supplier has a reoccurring elevated blood sugar, this remains elevated in the newborn after delivery. It will take several days or longer for newborns to stabilize and return to a normal insulin level on their own.  

Stressed or Sick Newborns (2) 

• Shock 
• Infection 
• Respiratory disease 
• Cardiac disease 
• Hypothermia 
• Hypoxia 
• Perinatal Stress 
• All of these newborns have higher energy needs, causing a rapid depletion of glycogen stores they have built up

Medications During Pregnancy (2) 

• Maternal IV dextrose 
• Tricyclic antidepressants 
• Thiazide diuretics 
• Beta-Blockers 
• Sulfonylureas 
• Beta-sympathomimetic 

Potential Causes (2) 

• Inadequate glycogen stores 
• Decreased glucose production 
• Hyperinsulinemia 
• Increased glucose utilization 

Signs & Symptoms 

With neonatal hypoglycemia, there are two varying pathways in the development and display of this condition. Some newborns may have hypoglycemia and not present any signs. For these newborns relying on your history and reviewing your risk factors to initiate blood glucose monitoring protocols may be your only clinical asset to identify and treat neonates. Signs and symptoms for neonatal hypoglycemia can be split into three different categories.  

General Findings (2)

• Abnormal cry 
• Poor feeding 
• Hypothermia 
• Diaphoresis 

Neurologic Signs (2)

• Tremors 
• Jitteriness 
• Irritability 
• Hypotonia 
• Lethargy 
• Seizures 

Cardiorespiratory Signs (2)

• Tachypnea 
• Apnea  
• Cyanosis 

Monitoring & Screening 

After reviewing these signs and symptoms listed above, this list can be related to other diagnoses. Using blood glucose monitoring as part of an overall assessment is extremely important to provide safe and effective overall patient care. If your facility utilizes a hypoglycemic protocol having a clear and universal understanding between staff in the care team leads to prompt and effective evaluation. Unfortunately, there isn’t a straightforward or universal standard for neonatal glucose levels (3). So, when the opportunity for a newborn to have monitoring and evaluation for neonatal hypoglycemia is present, adhering to your facility’s guidelines will then guide your clinical interventions and continued monitoring. To assist with the understanding of a monitoring and evaluation tool, we will review a sample format from the American Academy of Pediatrics.  

(1) 

When reviewing this algorithm for screening newborns for hypoglycemia, it utilizes a symptomatic versus asymptomatic starting point. Using a symptomatic versus asymptomatic screening assessment approach enables the health care team to cover a widespan of newborns to help ensure a wide range of neonates born is examined for potential hypoglycemic issues.  

Obtaining a bedside glucose measurement is typically performed via heel stick. The measurement obtained from a heel stick is considered capillary, while serum glucose for the lab will be done through a venous stick from accessing a vein.  

Using an approved single use warming pack over the heel will increase success for the heel stick due to increased blood flow. To prevent structural damages to the foot, placement of the heel stick is critical. While deciding the placement of the heel stick, use an imaginary line from the middle of the big toe and one between the fourth and fifth toes, then drawing that imaginary line down to the bottom of the foot and using the outer space of that line for placement (4). In addition, using the correct size lancet for premature newborns or term newborns to prevent possible long-term damage should always be considered.  

When low blood sugar is obtained, confirming with lab serum glucose is necessary because of the possible inaccuracy with bedside glucose monitoring. Treatment shouldn’t be delayed while waiting for serum glucose results to run (3).  

Diagnosis: Acute & Chronic 

Neonatal hypoglycemia is diagnosed from symptoms or when the glucose level falls below a safe range (5). Newborns have a normal physiologic transitional response after birth but separating these newborns from those with acute or chronic disorders is very important (3).  When evaluating a neonate with hypoglycemia, reviewing in-patient glucose assessments, risk factors, physical assessments, and feeding patterns are critical in the overall clinical picture for the ongoing treatment.  

Persistent hypoglycemia in newborns occurs when plasma glucose concentrations are persistently low beyond the first 48 hours of life or the use of glucose infusion for beyond the 48 hours of life is required (3). Establishing the pattern between low levels of glucose and normal trends throughout these first days of life will help determine treatment and effectiveness of interventions. Obtaining additional lab work may be necessary to continue to build this clinical picture and lead to your causing indicator.  

Additional Labs (1) 

• HCO3 (hydrogen carbonate) 
• BOHB (beta-hydroxybutyrate) 
• Lactate 
• GH (growth hormones) 
• FFA (Free Fatty Acids) 

These labs will assist with determining our underlying causative factor for neonatal hypoglycemia.  

BOHB and FFA 

• Low Level 
• Genetic Hyperinsulinism 
• Hypopituitarism in newborns 
• Transitional neonatal hypoglycemia 
• Perinatal stress hyperinsulinism 
• Low BOHB and high FFA 
• Fatty acid oxidation defects 
• High BOHB 
• Ketotic hypoglycemia 
• Glycogenesis 
• GH deficiency 
• Cortisol deficiency 

Lactate 

• High level 
• Gluconeogenesis defects 

Treatment 

Again, separating our treatment approach between asymptomatic and symptomatic newborns is important to determine treatment aggressiveness. The lowest level of acceptable glucose at this time is 25mg/dL after the first feeding; levels requiring intervention are between 25-40mg/dL (1).  

When utilizing the screening algorithm from AAP earlier in this course, for asymptomatic newborns with risk factors that are found to have an initial low glucose level, we should feed, then recheck in one hour. If the glucose level remains low on the recheck, a serum collection at that time should be done for the lab to analyze. 

 Initiating a standard facility protocol for IV glucose administration should be performed and not delay treatment while waiting for the serum results.  Taking more aggressive measures when neonates are symptomatic is the key approach to prevent detrimental damage. Initiating IV glucose administration with the initial hypoglycemic episode before attempting another feeding is the big difference in treatment plans between asymptomatic and symptomatic newborns.  Continuing with glucose monitoring parameters throughout their hospital stay until newborns appear to have stabilized their glucose levels is shown to be evidence-based practice. When newborns continue to be asymptomatic and are over the 4 hours of age mark, using a less than 35mg/dL goal is used. When levels are less than this goal mark, the same asymptomatic intervention and screening steps are taken.  

The use of dextrose gel has been seen to be effective for neonates that are asymptomatic with low blood glucose levels. Utilizing dextrose gel in conjunction with re-feeding has been shown to have improved results on the retesting at the one-hour mark (3).  

When a newborn is applicable for discharge post-delivery, having all pertinent information documented for the newborn’s provider to review will determine the timing of follow-up appointments or potential need for referral to pediatric endocrinology. To ensure newborns have successfully transitioned before discharge, having glucose measurements that reflect normal ranges throughout cycles of feeding and fasting are your key indicators for sufficient metabolic functioning (3). Glucose expectations at each of these occurrences should be determined to achieve known goals for the entire healthcare team and parent expectations. 

Non-Treatment Implications 

At this time, outcomes in neonates with asymptomatic hypoglycemia remain unclear. There is a known correlation to brain injury for symptomatic neonates, providing a clear indication for successful monitoring and prompt treatment. Unfortunately, defining parameters on glucose concentrations or harmful lengths of hypoglycemia in neonates is still unclear (3). Continued research is also indicated to define criteria for neonates delivered at varying gestational ages.  

Patient Education 

When reviewing the medical information for overall risk factors, initiating a conversation with parents over general expectations is very beneficial. When a newborn has known risk factors, reviewing and explaining these particular risk factors present and the potential for neonatal hypoglycemia will help create an overall expectation for parents. 

• Review the assessments and monitoring plan for their newborn’s blood glucose measurement frequency, presenting information if they are asymptomatic or symptomatic, so there are clear expectations.  
• Discuss treatment information if blood sugar is below the safe range and why the treatment is important. 
• Discuss collection of blood for testing, including heel sticks, venous draws, and dressings. Always provide reassurance to parents and try to address any questions they have.  
• Refer them to their newborn care provider if you are unable to answer any of their questions.

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