Neonatal Hypoglycemia: Up To Date
Terms
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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