Glucose Homeostasis and Hypoglycaemia ✅

Question 1

How does the glucose requirements of neonates compare to adults?

Answer 1

3x greater in neonates

Question 2

Why do neonates have a higher glucose requirement than adults?

Answer 2

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

Question 3

How do neonates meet their increased need for glucose?

Answer 3

They have a higher hepatic glucose production rate

Question 4

What is the hepatic glucose production rate of a neonate?

Answer 4

Up to 60mg/kg/minute

Question 5

What processes are involved in energy metabolism in a neonate?

Answer 5

• Glycogen production and glycogenolysis
• Gluconeogenesis
• Lipolysis

Question 6

Where does glycogen production and glycogenolysis occur in neonates?

Answer 6

Mainly in the liver and muscle

Question 7

Why are liver glycogen stores important?

Answer 7

They are rapidly available for breakdown to glucose

Question 8

What is gluconeogenesis?

Answer 8

The process of glucose synthesis

Question 9

What substrates are used in gluconeogenesis?

Answer 9

• Amino acids
• Lactate
• Pyruvate
• Glycerol

Question 10

What is lipolysis?

Answer 10

Breakdown of lipids into fatty acids and triglycerides

Question 11

What can fatty acids and triglycerides be metabolised into?

Answer 11

Ketone bodies

Question 12

What are ketone bodies important for?

Answer 12

Important substrate for the brain

Question 13

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

Answer 13

Yes

Question 14

What closely controls glucose homeostasis?

Answer 14

Endocrine hormones

Question 15

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

Answer 15

• Insulin
• Glucagon
• Cortisone
• Growth hormones

Question 16

What effect does insulin have on blood glucose?

Answer 16

It reduces it

Question 17

How does insulin lower blood glucose?

Answer 17

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

Question 18

What effect does glucagon have on blood glucose?

Answer 18

It raises it

Question 19

How does glucagon raise blood glucose?

Answer 19

Stimulating glycogen breakdown

Question 20

Can a fetus make glucose from glycogen?

Answer 20

No

Question 21

How does a fetus obtain glucose?

Answer 21

It is completely dependent on the placenta to provide glucose

Question 22

Does a fetus make glycogen?

Answer 22

Yes

Question 23

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

Answer 23

Only a few hours of fasting

Question 24

What happens at birth, regarding glucose supplies?

Answer 24

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

Question 25

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

Answer 25

- Glucose levels fall | - Surge of glucagon and fall in insulin level

Question 26

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

Answer 26

A few hours

Question 27

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

Answer 27

Alternative energy substrates, such as ketone bodies

Question 28

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

Answer 28

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

Question 29

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

Answer 29

- Maternal diabetes mellitus - Decreased glycogen stores - Increased requirements and impaired metabolism

Question 30

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

Answer 30

Secondary to exposure to high blood glucose in utero

Question 31

Why might babies have decreased glycogen stores?

Answer 31

- IUGR | - Preterm

Question 32

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

Answer 32

Sepsis

Question 33

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

Answer 33

Lack of consensus about what constitutes hypoglycaemia

Question 34

What can severe and prolonged symptomatic hypoglycaemia lead to?

Answer 34

Poor prognosis in terms of abnormal neurodevelopment or death

Question 35

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

Answer 35

2.6mmol/L

Question 36

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

Answer 36

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

Question 37

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

Answer 37

They are able to utilise ketones and other energy substrates

Question 38

What symptoms do most babies with hypoglycaemia have?

Answer 38

Most are asymptomatic

Question 39

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

Answer 39

- Jitteriness - Irritability - High-pitched cry

Question 40

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

Answer 40

- Depressed consciousness - Lethargy - Hypotonia

Question 41

What can severe hypoglycaemia result in?

Answer 41

- Apnoea - Coma - Seizures

Question 42

How is hypoglycaemia prevented in infants with risk factors?

Answer 42

- Provision of energy - Good temperature control - Treatment of any underlying cause, e.g. infection

Question 43

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

Answer 43

- Enterally (early and frequent feeds) | - Parenterally

Question 44

What monitoring should infants with hypoglycaemia have?

Answer 44

BM monitoring until >2.6mmol/L

Question 45

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

Answer 45

- Extra feeds | - IV glucose

Question 46

What does symptomatic hypoglycaemia require in terms of management?

Answer 46

Urgent correction and investigation

Question 47

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

Answer 47

A laboratory measurement

Question 48

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

Answer 48

They do not measure blood glucose levels accurately

Question 49

When does hypoglycaemia require detailed investigation?

Answer 49

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

Question 50

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

Answer 50

- Antenatal | - Neonatal

Question 51

What are the antenatal causes of transient hypoglycaemia?

Answer 51

Maternal diabetes mellitus

Question 52

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

Answer 52

- Insulin-dependent | - Gestational

Question 53

What are the neonatal causes of transient hypoglycaemia?

Answer 53

- IUGR - Large for gestational age - Preterm - Infection - Iatrogenic - Polycythaemia - Perinatal asphyxia - Rhesus disease - Hypothermia

Question 54

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

Answer 54

Reduced feeds with inadequate IV glucose

Question 55

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

Answer 55

- Reduced glucose availability | - Increased glucose consumption

Question 56

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

Answer 56

- IUGR - Prematurity - Panhypopituitarism - Cortisol deficiency - Growth hormone deficiency - Glucagon deficiency - Accelerated starvation (ketotic hypoglycaemia) - Inborn errors of metabolism

Question 57

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

Answer 57

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

Question 58

What investigations should be done in persistent hypoglycaemia?

Answer 58

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

Question 59

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

Answer 59

At the time of hypoglycaemia

Question 60

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

Answer 60

Insulin suppression

Question 61

What treatments can achieve insulin suppression?

Answer 61

- Diazocide - Somatostatin analogues (octreotide) - Pancreatic resection - Glucagon

Question 62

What might be required for specific endocrine deficiencies causing hypoglycaemia?

Answer 62

Hormone replacement therapy