Hypoglycemia Flashcards
Why is glucose so important for the newborn?
The brain uses it exclusively as a substrate; babies have a higher brain to bodyweight ratio
Where does the fetus get its glucose from?
Maternal circulation via facilitated diffusion
What results from the high insulin:glucagon ratio in the fetal circulation?
increased glycogen synthesis and decreased glycogenolysis
Once born what happens to maintain glucose homeostasis?
- Catecholamine release -> glucagon release -> glycogenolysis
- Synthesis of hepatic enzymes involved in gluconeogenesis
Hormones that play a role in glucose homeostasis?
Insulin, glucagon, adrenaline, cortisol, growth hormone
Which part of the nervous system also gets stimulated during starvation?
SNS – causes epinephrine release from adrenal glands = release of glucose from liver
What does growth hormone and cortisol do?
reduces rate at which body utilizes glucose supply during hypoglycaemia
What is transitional hypoglycaemia?
Drop in glucose levels in the first 2-3h of life; usually benign, occurs in 10% of term infants
Risk factors for neonatal hypoglycemia?
SGA, LGA, IUGR, Prematurity, IDM, sepsis
2 main causes of neonatal hypoglycaemia? + 1 other
1) excess insulin production
2) inadequate glycogen stores
3) increased glucose use
Causes of hyperinsulinemia?
1) IDM
2) LGA/macrosomic babies (>4kg)
3) PHHI (persistent hyperinsulinism hypoglycaemia of infancy) - release of insulin even at low levels
4) Beckwith-Wiedemann Syndrome
5) Sotos Syndrome
Causes of inadequate glycogen stores?
1) prematurity
2) SGA
3) IUGR
4) perinatal asphyxia
5) starvation
Causes of increased glucose consumption?
1) hypothermia
2) sepsis
3) polycythemia
4) growth hormone/cortisol deficiency
5) inborn errors of metabolism
6) adrenal insufficiency
7) liver disease
Neurogenic symptoms of neonatal hypoglycemia? - i.e. sympathetic stimulation
jitteriness, pallor, temp instability, tachy, vomiting
Neuroglycopenic symptoms of neonatal hypoglycaemia? - i.e. reduced glucose to brain
apnea, cyanosis, hypotonia, lethargy, unresponsiveness, seizures, weak/high pitched cry, coma
When should you screen & what are the cutoffs?
- in first 2h if unwell; treat if <2.6mmol/L
- If well but at risk, check at 2h, after 1 effective feed and every 3-6h after that (before feeds). Aim for blood glucose levels above 2 mmol/L at 2 hours of age and above 2.6 mmol/L at subsequent checks
Treatment options?
increase BF frequency, supplementation, 40% dextrose gel, IV glucose, IV glucagon
IV glucose therapy
start with a 10% dextrose solution at 80 mL/kg/day or a single minibolus of 2mL/kg 10% dextrose solution. Wean when glucose levels have been stable for 12-24h
IV glucagon therapy
IV bolus at 0.1-0.3 mg/kg or by infusion at 10-20 ug/kg/h.
When to stop screening?
In infants of diabetic mothers or those who are large for gestational age, hypoglycaemia usually happens within the first 12 hours of life (levels >2.6mmol/L). In infants who are small for gestational age or premature, hypoglycaemia usually happens within the first 36 hours of life.
