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TAS Neonatal Medicine ✅ > Glucose Homeostasis and Hypoglycaemia ✅ > Flashcards

Glucose Homeostasis and Hypoglycaemia ✅ Flashcards

1
Q

How does the glucose requirements of neonates compare to adults?

A

3x greater in neonates

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2
Q

Why do neonates have a higher glucose requirement than adults?

A

Glucose is the primary fuel for the brain, and neonates have a larger brain to body size ration

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3
Q

How do neonates meet their increased need for glucose?

A

They have a higher hepatic glucose production rate

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4
Q

What is the hepatic glucose production rate of a neonate?

A

Up to 60mg/kg/minute

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5
Q

What processes are involved in energy metabolism in a neonate?

A
  • Glycogen production and glycogenolysis
  • Gluconeogenesis
  • Lipolysis
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6
Q

Where does glycogen production and glycogenolysis occur in neonates?

A

Mainly in the liver and muscle

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7
Q

Why are liver glycogen stores important?

A

They are rapidly available for breakdown to glucose

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8
Q

What is gluconeogenesis?

A

The process of glucose synthesis

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9
Q

What substrates are used in gluconeogenesis?

A
  • Amino acids
  • Lactate
  • Pyruvate
  • Glycerol
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10
Q

What is lipolysis?

A

Breakdown of lipids into fatty acids and triglycerides

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11
Q

What can fatty acids and triglycerides be metabolised into?

A

Ketone bodies

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12
Q

What are ketone bodies important for?

A

Important substrate for the brain

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13
Q

Can glycerol metabolised from adipose tissue be directed utilised through gluconeogenesis?

A

Yes

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14
Q

What closely controls glucose homeostasis?

A

Endocrine hormones

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15
Q

What endocrine hormones are involved in the control of glucose homeostasis?

A
  • Insulin
  • Glucagon
  • Cortisone
  • Growth hormones
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16
Q

What effect does insulin have on blood glucose?

A

It reduces it

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17
Q

How does insulin lower blood glucose?

A

By stimulating the formation of glycogen and glucose uptake into tissue cells

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18
Q

What effect does glucagon have on blood glucose?

A

It raises it

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19
Q

How does glucagon raise blood glucose?

A

Stimulating glycogen breakdown

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20
Q

Can a fetus make glucose from glycogen?

A

No

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21
Q

How does a fetus obtain glucose?

A

It is completely dependent on the placenta to provide glucose

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22
Q

Does a fetus make glycogen?

A

Yes

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23
Q

How long are fetal liver stores of glycogen sufficient for at term?

A

Only a few hours of fasting

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24
Q

What happens at birth, regarding glucose supplies?

A

The fetus is disconnected from the continuous supply of glucose and has to adapt to intermittent feeding

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25
Q

What is the result in the changes in glucose supply at birth?

A
  • Glucose levels fall

- Surge of glucagon and fall in insulin level

26
Q

How long does it take for a newborn baby to switch on gluconeogenesis?

A

A few hours

27
Q

What is relied on for energy in the first few days of life?

A

Alternative energy substrates, such as ketone bodies

28
Q

Why are alternative energy substrates relied on for the first few days of life?

A

Because an infants food volume intake is very low, with only a small volume of colostrum

29
Q

What are the risk factors for transient hypoglycaemia of the neonate?

A
  • Maternal diabetes mellitus
  • Decreased glycogen stores
  • Increased requirements and impaired metabolism
30
Q

Why are babies born to mothers with diabetes mellitus at increased risk of transient hypoglycaemia?

A

Secondary to exposure to high blood glucose in utero

31
Q

Why might babies have decreased glycogen stores?

A
  • IUGR

- Preterm

32
Q

Give an example of a cause of increased glucose requirements and impaired metabolism

A

Sepsis

33
Q

What is the problem with the definition of hypoglycaemia in the newborn?

A

Lack of consensus about what constitutes hypoglycaemia

34
Q

What can severe and prolonged symptomatic hypoglycaemia lead to?

A

Poor prognosis in terms of abnormal neurodevelopment or death

35
Q

What is generally used as the threshold for hypoglycaemia in neonates?

A

2.6mmol/L

36
Q

Why is the use of 2.6mol/L as a threshold for hypoglycaemia controversial?

A

Many normal breastfed infants tolerate lower glucose levels in the first few days of life, and unnecessary intervention should be avoided

37
Q

Why are normal breastfed infants able to tolerate lower glucose levels in the first few days of life?

A

They are able to utilise ketones and other energy substrates

38
Q

What symptoms do most babies with hypoglycaemia have?

A

Most are asymptomatic

39
Q

What are the symptoms of hypoglycaemia in a neonate when present?

A
  • Jitteriness
  • Irritability
  • High-pitched cry
40
Q

What are the symptoms of more severe hypoglycaemia in a neonate?

A
  • Depressed consciousness
  • Lethargy
  • Hypotonia
41
Q

What can severe hypoglycaemia result in?

A
  • Apnoea
  • Coma
  • Seizures
42
Q

How is hypoglycaemia prevented in infants with risk factors?

A
  • Provision of energy
  • Good temperature control
  • Treatment of any underlying cause, e.g. infection
43
Q

How can energy be provided in infants with risk factors for neonatal hypoglycaemia?

A
  • Enterally (early and frequent feeds)

- Parenterally

44
Q

What monitoring should infants with hypoglycaemia have?

A

BM monitoring until >2.6mmol/L

45
Q

What may be needed to maintain BMs >2.6mmol/L in neonates with hypoglycaemia?

A
  • Extra feeds

- IV glucose

46
Q

What does symptomatic hypoglycaemia require in terms of management?

A

Urgent correction and investigation

47
Q

What should be done if hypoglycaemia is identified using a bedside glucometer?

A

A laboratory measurement

48
Q

Why should a laboratory measurement be obtained when hypoglycaemia is identified by a bedside glucometer?

A

They do not measure blood glucose levels accurately

49
Q

When does hypoglycaemia require detailed investigation?

A

Prolonged, persistent, or refractory hypoglycaemia despite glucose intake of over 8-10mg/kg/min

50
Q

What can the causes of transient neonatal hypoglycaemia be divided into?

A
  • Antenatal

- Neonatal

51
Q

What are the antenatal causes of transient hypoglycaemia?

A

Maternal diabetes mellitus

52
Q

What kind of maternal diabetes mellitus can cause transient hypoglycaemia in the neonate?

A
  • Insulin-dependent

- Gestational

53
Q

What are the neonatal causes of transient hypoglycaemia?

A
  • IUGR
  • Large for gestational age
  • Preterm
  • Infection
  • Iatrogenic
  • Polycythaemia
  • Perinatal asphyxia
  • Rhesus disease
  • Hypothermia
54
Q

What are the iatrogenic causes of transient hypoglycaemia of the neonate?

A

Reduced feeds with inadequate IV glucose

55
Q

What can the causes of persistent neonatal hypoglycaemia be divided into?

A
  • Reduced glucose availability

- Increased glucose consumption

56
Q

What are the causes of reduced glucose availability leading to persistent neonatal hypoglycaemia?

A
  • IUGR
  • Prematurity
  • Panhypopituitarism
  • Cortisol deficiency
  • Growth hormone deficiency
  • Glucagon deficiency
  • Accelerated starvation (ketotic hypoglycaemia)
  • Inborn errors of metabolism
57
Q

What are the causes of increased glucose consumption leading to persistent neonatal hypoglycaemia?

A
  • Congenital hyperinsulinism
  • Transient neonatal hyperinsulinism
  • Maternal diabetes
  • Persistent hypoglycaemic hyperinsulinism of infancy
  • Beckwith-Wiedemann syndrome
  • Rhesus haemolytic disease
  • Perinatal asphyxia
58
Q

What investigations should be done in persistent hypoglycaemia?

A
  • Glucose
  • U&E
  • pH
  • Liver function tests
  • Lactate
  • Pyruvate
  • Free fatty acids
  • ß-hydroxybutyrate
  • Acylcarnitine
  • Ammonia
  • Insulin
  • C-peptide
  • Cortisol
  • ACTH
  • Growth hormone
59
Q

When should blood tests for investigation into persistent hypoglycaemia be taken?

A

At the time of hypoglycaemia

60
Q

What treatment might be required in prolonged and refractory hypoglycaemia due to hyperinsulinism?

A

Insulin suppression

61
Q

What treatments can achieve insulin suppression?

A
  • Diazocide
  • Somatostatin analogues (octreotide)
  • Pancreatic resection
  • Glucagon
62
Q

What might be required for specific endocrine deficiencies causing hypoglycaemia?

A

Hormone replacement therapy

TAS Neonatal Medicine ✅ (35 decks)

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