A 1-hour-old male was seen in the labor and delivery room. He was born at 38 weeks by spontaneous vaginal delivery after a 23 hour labor to a G2 P2 female who had gestational onset diabetes controlled with metformin. The baby had already attempted to feed.
The pertinent physical exam showed a vigorous and pink infant with heart rate of 120/minute, respirations of 32/minute and temperature of 37.2 °C. His weight was 4253 grams (> 90%), length was 53.5 cm (75%) and head circumference of 37 cm (75%). Ballard exam was consistent with 38 weeks. He had some molding of his head. His examination was otherwise unremarkable.
The diagnosis of of a healthy male who was large for gestational age born to a mother with gestational onset diabetes was made. As the medical student and intern were new to the service, the newborn attending reviewed the risk factors for potential asymptomatic hypoglycemia and how it was monitored for. “The nurses will do the glucose checks at timed intervals for the first 24+ hours of life and if the baby is less 25 they need to be treated right away usually with IV glucose. We don’t do that here and we need to call the NICU to get help right away. If the glucose is 25-40 then we usually treat with oral glucose and feed the baby. If it is 40-50 we usually feed the baby. You can give gel or feed again if the baby is still low after the first treatment, but I usually start thinking then why the treatment may not be working. Certainly if it is not working after the second try I am calling the NICU for some more help and potentially transferring the baby. These are general numbers for babies that are asymptomatic. Any baby that is symptomatic needs to be examined and have a glucose check and treated more aggressively. It just depends on the situation. Most of the time the babies are fine with no hypoglycemia, or they just need to eat and are fine after they do. But if they continue to have persistently low glucoses then we need to pay attention. This is where you find our exact protocol so if you need to know what to do you can follow it,” he said.
Discussion
The brain must use glucose as its fuel source. The brain only has a few minutes of stored glucose available and therefore needs a steady supply. If the glucose supply is not available it can have neurological consequences. The brain can also use ketones and lactate if they are in high enough quantities but generally they are not sufficiently high to be a glucose substitute. Adult brains use about 50% of total glucose utilization. Infants and children need 2-3 x the adult glucose utilization.
As plasma glucose (PG) decreases the following occurs:
| <85 mg/dL | Insulin secretion is suppressed – stops glucose storage |
| 65-70 mg/dL | Glucagon secretion and sympathoadrenal system activation – releases from storage in mainly liver |
| <65 mg/dL | Cortisol and growth hormone increase – release (from fat and other tissues) and maintenance of glucose levels |
| 55-65 mg/dL | Brain glucose utilization becomes limited |
| <55 mg/dL | Neurological symptoms are perceived by patient and they search for food or help |
| <50 mg/dL | Cognitive function is impaired |
Physiologic symptoms that occur in response to hypoglycemia include:
- Adrenergic
- Anxiety
- Palpitations
- Tremor
- Cholinergic
- Hunger
- Paresthesia
- Sweating
- Neurological
- Confusion
- Coma
- Seizures
PG is the most accurate. Whole blood measurements can be off up to ± 10-15 mg/dL. Point of care glucose measurements can be helpful but clinical laboratory confirmation is needed for accuracy during a hypoglycemic event.
Learning Point
“Clinical hypoglycemia is defined as a PG concentration low enough to cause symptoms and/or signs of impaired brain function.” It is not a specific number. Normal glucose values during the first 48 hours of life are generally considered to be 60-110 mg/dL, but it always will depend on the clinical situation. True neonatal hyperglycemia is rare. After birth, PG concentrations decrease below those normally seen after 48 hours of life due to transient, mild hyperinsulinism. This hyperinsulinism can decrease the mean PG to ~ 55-65 mg/dL during the first 48 hours. As newborns and other young infants also may be asymptomatic but have clinically significant hypoglycemia, they may need to be treated. Treatment options include feeding the baby (breast milk or formula), buccal dextrose gel, or intravenous glucose. Infants at risk for asymptomatic hypoglycemia include those who are large-for-gestation age, small-for-gestational age, intrauterine growth retardation, late preterm, and infants of diabetic mothers. Other common reasons may be infection or perinatal stress. These infants are often monitored by clinical protocol after birth because the infants may be asymptomatic.
“After the first 48 hours of life, PG concentration and the physiology of glucose homeostasis do not differ to any great extent with age. Mean PG concentration in the postabsorptive state in normal neonates after ~2 days of age and in infant and children does not differ from that in adults (70-100 mg/dL [3.9-5.5 mmol/L])(emphasis added); however, children under 4 years may have a PG concentration <70 mg/dL (3.9 mmol/L) and hyperketonemia after overnight fasting because of limited fasting tolerance." (emphasis added)
Questions for Further Discussion
1. What is in the differential diagnosis of true persistent hypoglycemia in the newborn period?
2. What is in the differential diagnosis of true persistent hypoglycemia after the newborn period?
3. What is the “glucose protocol” in your newborn nursery to screen for asymptomatic hypoglycemia?<br
Related Cases
- Disease: Hypoglycemia
- Symptom/Presentation: Health Maintenance and Disease Prevention
- Specialty: Neonatology
- Age: Newborn
To view pediatric review articles on this topic from the past year check PubMed.
Evidence-based medicine information on this topic can be found at SearchingPediatrics.com and the Cochrane Database of Systematic Reviews. Information prescriptions for patients can be found at MedlinePlus for this topic: Hypoglycemia
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Thornton PS, Stanley CA, De Leon DD, et al. Recommendations from the Pediatric Endocrine Society for Evaluation and Management of Persistent Hypoglycemia in Neonates, Infants, and Children. J Pediatr. 2015;167(2):238-245. doi:10.1016/j.jpeds.2015.03.057
Lord K, De Leon DD. Hyperinsulinism in the Neonate. Clinics in Perinatology. 2018;45(1):61-74. doi:10.1016/j.clp.2017.10.007
Rozance PJ, Wolfsdorf JI. Hypoglycemia in the Newborn. Pediatric Clinics of North America. 2019;66(2):333-342. doi:10.1016/j.pcl.2018.12.004
Author
Donna M. D’Alessandro, MD
Professor of Pediatrics, University of Iowa