Hypoglycemia

Question 1

Why is glucose so important for the newborn?

Answer 1

The brain uses it exclusively as a substrate; babies have a higher brain to bodyweight ratio

Question 2

Where does the fetus get its glucose from?

Answer 2

Maternal circulation via facilitated diffusion

Question 3

What results from the high insulin:glucagon ratio in the fetal circulation?

Answer 3

increased glycogen synthesis and decreased glycogenolysis

Question 4

Once born what happens to maintain glucose homeostasis?

Answer 4

• Catecholamine release -> glucagon release -> glycogenolysis
• Synthesis of hepatic enzymes involved in gluconeogenesis

Question 5

Hormones that play a role in glucose homeostasis?

Answer 5

Insulin, glucagon, adrenaline, cortisol, growth hormone

Question 6

Which part of the nervous system also gets stimulated during starvation?

Answer 6

SNS – causes epinephrine release from adrenal glands = release of glucose from liver

Question 7

What does growth hormone and cortisol do?

Answer 7

reduces rate at which body utilizes glucose supply during hypoglycaemia

Question 8

What is transitional hypoglycaemia?

Answer 8

Drop in glucose levels in the first 2-3h of life; usually benign, occurs in 10% of term infants

Question 9

Risk factors for neonatal hypoglycemia?

Answer 9

SGA, LGA, IUGR, Prematurity, IDM, sepsis

Question 10

2 main causes of neonatal hypoglycaemia? + 1 other

Answer 10

1) excess insulin production
2) inadequate glycogen stores
3) increased glucose use

Question 11

Causes of hyperinsulinemia?

Answer 11

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

Question 12

Causes of inadequate glycogen stores?

Answer 12

1) prematurity
2) SGA
3) IUGR
4) perinatal asphyxia
5) starvation

Question 13

Causes of increased glucose consumption?

Answer 13

1) hypothermia
2) sepsis
3) polycythemia
4) growth hormone/cortisol deficiency
5) inborn errors of metabolism
6) adrenal insufficiency
7) liver disease

Question 14

Neurogenic symptoms of neonatal hypoglycemia? - i.e. sympathetic stimulation

Answer 14

jitteriness, pallor, temp instability, tachy, vomiting

Question 15

Neuroglycopenic symptoms of neonatal hypoglycaemia? - i.e. reduced glucose to brain

Answer 15

apnea, cyanosis, hypotonia, lethargy, unresponsiveness, seizures, weak/high pitched cry, coma

Question 16

When should you screen & what are the cutoffs?

Answer 16

• 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

Question 17

Treatment options?

Answer 17

increase BF frequency, supplementation, 40% dextrose gel, IV glucose, IV glucagon

Question 18

IV glucose therapy

Answer 18

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

Question 19

IV glucagon therapy

Answer 19

IV bolus at 0.1-0.3 mg/kg or by infusion at 10-20 ug/kg/h.

Question 20

When to stop screening?

Answer 20

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.