Hypoglycemia

  • Core 1 (Pre-Clerkship)
    • Biomedical Science
      • Biochemistry
        • Glycogen
        • Fatty Acid Oxidation and Gluconeogenesis
    • Integrative Science
      • Endocrinology: Hypoglycemia
  • Core 2 (Clerkship)
    • Pediatrics Clerkship Simulation - Seizure
  • Core 3 (Post Clerkship) Electives that may further knowledge - Peds Endocrinology, NICU

A 2 hour old infant born at 37 weeks presents with jitteriness. 

Infant born at 37 weeks via C-section. Prenatal course notable for mother with Type 1 diabetes and infant measuring large for gestational age (LGA), otherwise unremarkable. Infant breastfed within 1 hour of birth and was noted just now by nursing to be “jittery.” Point-of-care glucose was 38. 

Large infant, normocephalic, anterior fontanelle open, soft & flat. Heart regular rate & rhythm, lungs clear, abdomen normal with no hepatosplenomegaly. Normal infant reflexes including startle response & Moro reflex. Dry skin, no rashes. 

History:

  • Feeding history: when, how, how much? (breastfeeding time on each breast versus formula amount)
  • Birth history: gestational age, birth weight & percentile, maternal history (namely diabetes), maternal medications (especially beta blockers, terbutaline, oral hypoglycemia agents) 

Physical Exam:

  • Overall appearance 
  • Oropharynx (look for mucous membranes for hydration, oral lesions, other findings that could affect feeding). Observe a feed if you can!
  • Abdominal exam (look for hepatosplenomegaly)
  • Neurologic (look for suck & rooting reflex, abnormal movements) 

Lower glucose levels within the first 24-48 hours of life can be considered normal, as newborns adjust to maintaining blood glucose on their own (without the constant supply of glucose via mom’s placenta). Persistent hypoglycemia, however, can be due to a number of factors: 

  • Infant of diabetic mother (as baby is naturally exposed to insulin & glucose swings), or certain maternal medications (such as beta blockers, terbutaline, oral hypoglycemic agents)
  • Prematurity or low birth weight (due to immature system and low glycogen stores); small or large for gestational age (SGA or LGA)
  • Perinatal stress (such as hypoxia, preeclampsia, IUGR)
  • Sepsis or infection 
  • Endocrine or metabolic disorders
  • Congenital syndromes (eg, Beckwith-Wiedemann), abnormal pysical features (eg, midline facial malformations, microphallus)

  • Evaluate for symptoms (such as jitteriness, irritability, poor suck or refusal to eat, abnormal breathing, seizure) and risk factors for hypoglycemia (IDM, maternal medications, prematurity, SGA or LGA, sepsis or clinical instability) 
    • If symptomatic or risk factors: feed baby shortly after birth, and check post-feed glucose 
    • If low BG <40, infant should feed again and may need to give dextrose gel. 
    • Depending on how low glucose is (and how persistently low), baby may need repeat dextrose gel or IV dextrose. 
    • Recheck glucose to ensure proper response. 
  • If baby is persistently hypoglycemic, may need to be transferred to NICU for ongoing management. 
  • May need to send additional labs if persistently & critically low – this is called a critical sample and evaluates for additional endocrine & metabolic causes of hypoglycemia (including hyperinsulinism, hypopituitarism, problems with gluconeogenesis or glycogen storage, fatty acid oxidation disorders, etc.) 
  • Sugar-containing IV fluids are maintained via glucose infusion rate (GIR), and are titrated based on serial glucose checks. 

  • Hypoglycemia is defined differently in newborns – we generally accept glucoses as low as 40-50! Goal may differ from institution to institution, but at CHOP & Penn, goals for glucose are:
    • >40 for <24 hours of age 
    • >50 for 24-48 hours of age 
    • >60 for >48 hours of age 
  • Most cases of hypoglycemia are asymptomatic in newborns. First line treatment is feeding and dextrose oral gel. Formula can be used to supplement feeds if the baby is still hypoglycemic and/or if there are concerns about adequate intake with breastfeeding. 

Click the drop down to reveal the correct answers

Q1: You are in the newborn nursery and are called to evaluate a 6 hour old infant born at 36 weeks, due to concerns for poor feeding and intermittent shaking. Which of the following most increases this infant’s risk of hypoglycemia?  

  1. Birth weight at 30th percentile for gestational age 
  2. Gestational age of 36 weeks 
  3. Maternal sertraline use 
  4. Paternal family history of diabetes  
  5. Parental desire to use formula 

Answers:

Q1: (B) prematurity is the best option here. Birthweight <10%ile (SGA) or >90%ile (LGA) increases risk of hypoglycemia. Maternal medications including beta blockers, terbutaline, and oral hypoglycemia agents increase risk of infant hypoglycemia; there is no known association with sertraline. While family history is important, most relevant would be maternal diabetes during pregnancy. Formula use is not associated with hypoglycemia, and is in fact a supplemental treatment option if the infant is hypoglycemic and not breastfeeding well.