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Neonatal Hypoglycemia: Up To Date

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Persistent or recurrent hypoglycemia can lead to what?
neurologic sequelae
What % of normal newborns can't maintain a plasma glucose concentration above 30 mg/dL if first feeding is delayed 3 to 6 hrs?
10%
What is definition of hypoclycemia?
It's controversial. Depends on gestational and postnatal age.
At birth, how does umbilical venous plasma glucose conc compare to maternal venous glucose conc?
60 to 80% of mom's
What happens to gluc conc after birth in normal baby?
Drops after 2hrs to nadir of no less than 40 mg/dL and stabilizes to 45-80 mg/dL by 4 to 6hrs.
How is gluc maintained after birth?
breakdown of hepatic glycogen (glycogenolysis) in response to epinephrine and glucagon; also falling insulin levels
When is glycogen depleted after birth?
8 to 12hrs and then glucose levels are maintained by synthesis of gluc from LAG [lactate, alanine, glycerol (gluconeogenesis)]
2 basic reasons for hypoglycemia?
diminished glucose supply (problem with glycogenolysis or gluconeogenesis) or overconsumption
When is glycogen deposited during pregnancy? Why is that relevant?
3rd trimester

premature babies will have diminished reserves
Why do babies with intrauterine growth restriction (IUGR) have reduced glycogen stores?
low insulin levels and chronic intrauterine hypoxia, which leads to inefficient anaerobic utilization of glucose
What endocrine disorders can cause hypoglycemia?
Deficiency in hormones regulating glucose homeostasis:

- cortisol
- growth hormone
- epinephrine
- glucagon

Can be isolated or associated with pituitary, hypothalamic or adrenal insufficiency
How does a hypothermic infant get hypoglycemic?
overuse of glucose
What medication taken by mom can lead to infant hypoglycemia?
propranolol, due to the interruption of stimulation of glycogenolysis by epinephrine
What is the most common clinical situation in which hyperinsulinism causes infant hypoglycemia?

Is the hypoglycemia persistent or transient?
IDM (infant of diabetic mother), but the hypoglycemia is usually transient
Name 4 situations associated with hyperinsulinism and transient infant hypoglycemia.
1. IDM
2. Beckwith-Wiedemann syndrome
3. erythroblastosis
4. perinatal asphyxia
About what fraction of IDM's get hypoglycemia (<40 mg/dL)?
1/4 (27% to be exact)
What is one theory on the cause of hypoglycemia in IDM's?
Pedersen hypothesis: intermittent maternal hyperglycemia causes fetal hyperglycemia, leading to premature maturation of pancreatic islet cells and hypertrophy of beta cells
What is Beckwith-Wiedermann syndrome?

What % have intermittent or persistent hypoglycemia?
fetal overgrowth syndrome causing:

- Macroglossia
- Abdominal wall defects
- Renal abnormalities
- Growth >90th %ile
- Ear creases or pits

50% have transient or prolonged hypoglycemia due to hyperinsulinism
Many hypoglycemic infants are asymptomatic, but, if symptomatic, what are clinical manifestations?
- jitteriness
- hypotonia
- altered consciousness
- apnea, bradycardia, cyanosis
- tachypnea
- poor suck or feeding
- hypothermia
- seizures
What are risk factors for hypoglycemia?
- premies
- SGA or LGA
- IDM's
- infants requiring intensive care (eg. sepsis or asphyxia)
- infants whose mothers took beta adrenergic or oral hypoglycemic agents

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