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Hypoglycaemia in childhood

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Investigations (see Investigations section)
If first episode of hypoglycaemia (BSL of <3.0 mmol/L), collect diagnostic blood samples prior to beginning treatment if possible. DO NOT delay correcting the hypoglycaemia if blood is difficult to obtain or patient is obtunded.
Bloods for ammonia and free fatty acids must be sent to the laboratory on ice and arrive within 30 minutes. Please notify the lab (ext 22000) on sending, or deliver the sample yourself.
Treat Hypoglycaemia (see Immediate Management section)
  1. Give 2 ml/kg 10% glucose (200 mg/kg glucose) followed by a continuous infusion of 5-8 mg/kg/min glucose (~3-5 ml/kg/hour of 10% glucose) to maintain and correct normoglycaemia and/or metabolic acidosis
  2. If IV access cannot be obtained give buccal glucose gel or insert intra-osseous line. 10% glucose can be given via intra-osseous route
Please note: standard paediatric rehydration solutions do not contain enough calories to correct hypoglycaemia and metabolic acidosis
Take any samples not collected above as soon as possible (see Investigations section below for more information)
Continue IV fluids (10% glucose + 0.9% sodium chloride + 20 mmol potassium chloride per 1000 mL bag depending on sodium and potassium) until eating and drinking normally. Decide on need for follow-up, referral or discussion with Metabolic (most complex hypoglycaemia) or Endocrine (if hyperinsulinism, adrenal or growth hormone deficiency suspected) services (see Follow-up section below)


Hypoglycaemia in children has recently been defined as a confirmed blood sugar level below 3.0 mmol/L1. 3.5 mmol/L should be used for children with inborn errors of metabolism (IEM) or hyperinsulinism.

The signs and symptoms of hypoglycaemia are variable and range from seizures and coma to nausea, abdominal pain and irritability. Signs and symptoms can be especially subtle in neonates. If intake has been poor, growth is abnormal or the child has a change in level of consciousness, a bedside blood sugar should be checked.

Causes of hypoglycaemia

Hypoglycaemia is a feature of many inherited metabolic and endocrine disorders. It can also occur, for reasons that are not completely understood, in children without a known disorder who are normally healthy (see tables below). This is a pattern of biochemical responses referred to as "idiopathic ketotic hypoglycaemia". This normally occurs in children between the ages of 18 months and 5 years and all children should have grown out of this by 10 years. Episodes of hypoglycaemia, particularly where there is also hypoketosis have significant morbidity and mortality, with the risk of sudden death and long term intellectual impairment.

When considering the differential diagnosis the questions to ask are:

  1. Is this ketotic or hypoketotic?
  2. Is the hypoglycaemia appropriate for the degree of fasting or 'metabolic stress'?
  3. Does the child have any clinical features to suggest this is not "idiopathic ketotic hypoglycaemia"?

Prolonged or recurrent hypoglycaemia and all hypoketotic hypoglycaemia must be discussed with the Metabolic consultant on call.

Causes of Hypoglycaemia after the neonatal period

Class of Disorder Principle Examples Clues to diagnosis
Idiopathic (most common) Idiopathic ketotic hypoglycaemia  - Normally occurs in the context of illness
- Normal exam
- Child is 18 months to 5 years
Counter-regulatory hormone deficiencies - Congenital adrenal hyperplasia
- Hypopituitarism
- Adrenal insufficiency   
- Ambiguous genitalia (CAH)
- Hyperpigmentation (CAH)
- Small phallus (hypopituitarism)
- Mid line defects (hypopituitarism)
Glycogen Storage Disorders (GSD)  Types I, III, VI, IX and rarely type 0  - Wakes at night to feed
- Hepatomegaly (except GSD0)
- Elevated CK (GSDIII)
- Lactate (GSDI)
- Urate (GSDI)
- Elevated cholesterol (GSDIII) or triglycerides
Gluconeogenic defects  - Fructose 1,6-bisphosphatase deficiency and
  ketolysis defects
- Metabolic acidosis
- Raised anion gap
- Lactic acidosis
Other inborn errors  Galactosaemia
- Hereditary fructose intolerance
- Glucose transporter defects i.e. Fanconi-
- Organic acidaemias
- Liver failure
- Multi-system disease
Hyperinsulinism - Focal (genetic or acquired)
- Diffuse (genetic)
- Hyperinsulinism-Hyperammonaemia
- (HIHA)
Secondary in:
- Congenital disorder of glycosylation
- Tyrosinaemia type 1
>10mg/kg/min glucose to maintain
Fatty Acid Oxidation defects (FAOD) - MCAD deficiency
- LCHAD deficiency
- VLCAD deficiency
- Others
- Hepatomegaly
- Elevated CK
- Cardiomyopathy

History and examination

A thorough history and examination is essential as a preliminary and often correct diagnosis can be made if these are performed by an experienced clinician.

History - key features

  • Age and timing of onset: IEMs often present after a prolonged fast (1st few days of life, intercurrent illness with decreased oral intake in childhood)
  • Previous stressors: How the child coped with illness, fasting, first few days of life
  • Dietary history: What time is dinner? What time do they wake up? Are they 'symptomatic' in the mornings prior to breakfast? Do they have a normal diet?
  • Birth history including where they were born as this is relevant to expanded newborn screening results
  • Growth and development: Is there any evidence of poor growth, overgrowth, developmental delay or regression?
  • Multi-system review: Is there a history of liver disease or possible rhabdomyolysis?

Examination - key features

  • Plot their growth including weight, head circumference and height
  • Do they have an enlarged liver?
  • Look for evidence of increased ACTH (hyperpigmentation), short stature (GH deficiency) or mid-line defects (cleft palate etc.)
  • If the child is developmentally normal and growing normally, then they are likely to have "idiopathic ketotic hypoglycaemia". These children are usually between 2 and 5 years old and are generally but not always relatively slim.


  • Ideally obtain blood for investigations prior to correction of the hypoglycaemia
  • If this is not achieved then samples at any time can be useful for some tests (see tables below)
  • The next specimen of urine passed must also be saved for measurement of organic acids and ketones
Samples to be taken during hypoglycaemia
Essential metabolic Essential Endocrine
Blood gas (including lactate)
Free fatty acids
Acylcarnitine profile (one spot on a Guthrie card)

Plasma amino acids
CK, LFT, Lipids, Urate
Pyruvate (if lactate high)
Urine organic acids, ketones
Insulin (avoid haemolysis)
Growth hormone
YOU WILL NEED A blood gas, 4 ml in lithium heparin (green tube), 1 ml EDTA and one blood spot or Guthrie card (or another 1 ml of lithium heparin) AND 3-5 ml urine. Note that bloods for ammonia and free fatty acids must be sent to the laboratory on ice and arrive within 30 minutes. Please notify the lab on sending (ext 22000, select chemistry option after hours), or deliver the sample yourself.    

Additional important notes:

  • The most important blood samples are: glucose, β-hydroxybutyrate and insulin, followed by those for cortisol and blood gas with a lactate
  • If these specimens are obtained a diagnosis can often be made without further provocation of overt hypoglycaemia
  • Some investigations can be done even if the patient is treated and no longer hypoglycaemic
Investigations that can be done when normoglycaemic
Patient Group Investigation
All patients  Lab glucose, B-hydroxybutyrate, acylcarnitine profile, urine organic acids
All patients (especially boys who are abnormally tanned and may have Addison's disease)  Early morning cortisol and ACTH (consider short synacthen) +/- VLCFA's 
Hepatomegaly or history suggestive of GSD  Consider molecular or enzyme testing for known GSD's (gene panel) 
Developmental delay, recurrent episodes, dysmorphism
Lactate, ammonia, transferrin isoforms, urine organic acids
Ketotic hypoglycaemia and abnormal growth Growth hormone stimulation test 

Immediate management

  1. DO NOT delay correcting the hypoglycaemia if blood is difficult to obtain or patient is obtunded
  2. Give 2 ml/kg of 10% glucose (200 mg/kg glucose) followed by a continuous infusion of 5-8 mg/kg/min glucose (~3-5 ml/kg/hour of 10% glucose) to correct and maintain normoglycaemia and/or metabolic acidosis
  3. Continue 10% glucose + 0.9% sodium chloride + 20 mmol potassium chloride per 1000 mL bag depending on sodium and potassium at maintenance + correction of deficit until the patient is eating and drinking properly and acidosis has resolved

    If an IV line cannot be placed the following management can occur:
  4. Give buccal glucose gel
  5. IV 10% glucose can be given through the intra-osseous route

If the patient has any diagnostic red flags the Metabolic team should be contacted. If in doubt, contact the Metabolic consultant on call. If an endocrine cause is suspected, contact the Paediatric Endocrine consultant on call

Prior to discharge

  1. Patients should be discharged once they are eating and drinking normally and it has been confirmed that they have no ketones in their blood or hypoglycaemia after a normal overnight fast
  2. If "idiopathic ketotic hypoglycaemia" is suspected but the presentation is not entirely typical, or you are wanting to better assess fasting tolerance to make sure they are 'safe' at home, it can be useful to get the parents to measure pre-breakfast β-hydroxybutyrate and glucose. This could be done at home with a ketone and glucose monitor, or in the lab pre-breakfast
  3. Unless there is a clear Endocrine diagnosis, consider discussing with the Metabolic consultant on 09 3670000 prior to discharge.

A controlled fasting test can be dangerous, should not be performed in the acute setting and is almost NEVER needed. Please contact the Metabolic consultant on call if it is felt to be necessary

Follow-up for presumed "Idiopathic Ketotic Hypoglycaemia"

  1. Unless it is 100% clear that this is physiological hypoglycaemia (i.e. ketotic hypoglycaemia that occurs in the context of prolonged fast with diarrhoea and vomiting for >24 hours), all patients should be followed up, either virtual or face-to-face, to review blood and urine results +/- decide if a referral to Metabolic or Endocrine teams is warranted
  2. When to refer to Metabolic clinic: If the hypoglycaemia is recurrent, severe or occurs after minimal provocation or fasting, or there are any concerning features in the family or patient history or examination
  3. Key discharge messages:
    1. Patient must not fast for greater than 12 hours and therefore go to bed on a full stomach
    2. Family should have a low threshold for admission to hospital if the child is not eating or vomiting more than twice in a row


  1. Ghosh A, Banerjee I, Morris AAM. Arch Dis Child, 2016;101:575-580.
  2. Sreekantam S, Preece MA, Vijay S, et al. Arch Dis Child Educ Pract Ed, 2017;102:28-36.

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Document Control

  • Date last published: 02 August 2018
  • Document type: Clinical Guideline
  • Services responsible: Metabolic, Paediatric Endocrinology
  • Author(s): Craig Jefferies, Emma Glamuzina, Natasha Heather
  • Owner: Emma Glamuzina
  • Editor: Greg Williams
  • Review frequency: 2 years

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