Hypoglycaemia

  • See also

    Diabetes Mellitus

    Key Points

    1. Hypoglycaemia is a Blood Glucose Level (BGL) low enough to cause signs and/or symptoms of impaired brain function and neurogenic response - generally BGL <3.3 mmol/L
    2. Infants with BGL <2.6 mmol/L and risk factors are at risk of acute and long-term neurological sequelae.
    3. Altered conscious state or seizures warrant prompt BGL assessment and management with a bolus of IV 10% Dextrose (2ml/kg) or IM glucagon.
    4. A venous blood gas and other diagnostic blood tests are important to identify an underlying cause but should not delay management.

    Background

    • Hypoglycaemia is a BGL low enough to cause signs and/or symptoms of impaired brain function and neurogenic response - generally BGL <3.3 mmol/L
    • In neonates <48hrs old, there is a lack of consensus on what constitutes normal BGL, however, BGL <2.6 warrants immediate intervention
    • Prolonged or recurrent hypoglycaemia, especially with clinical features, can cause long term neurological damage or death
    • Age at presentation can indicate the underlying case:

    Age

    Causes of Hypoglycaemia include

    Neonate < 48-72 hrs

    Prem, IUGR, perinatal asphyxia, hypothermia, sepsis, resp distress, diabetic mother, macrosomia, syndrome (e.g. Beckwith-Wiedemann), pancreatic dysfunction

    Neonate – 2yrs

    Congenital hyperinsulinism (most common cause of persistent hypoglycaemia <2yrs), inborn errors of metabolism, congenital hormone deficiencies (e.g. growth hormone deficiency)

    Child

    Accelerated starvation (previously known as “ketotic hypoglycaemia”)**, hypopituitarism, growth hormone deficiency

    Adolescent

    Insulinoma, adrenal insufficiency, eating disorder

    All ages

    Complication associated with Type 1 Diabetes Mellitus (see Diabetes Mellitus), other illness (e.g. sepsis, congenital heart disease, tumour, adrenal insufficiency)

    ** Accelerated starvation is a diagnosis of exclusion.  It requires a history of a prolonged fast (usually precipitated by a mild illness), with low BGL in association with ketonuria and/or ketonaemia and normalisation of BGL upon feeding.

    Assessment

    Red flag features in Red

    History:

    • Symptoms of hypoglycaemia
      • Palpitations, tremor, anxiety, sweating, hunger, paraesthesia
      • Severe hypoglycaemia - lethargy, irritability, uncharacteristic behaviour, hypothermia, confusion, coma, seizures
      • Neonate <48hrs - apnoea, hypotonia, jitteriness, poor feeding, high pitched cry
    • Dietary history, fasting/illness and relationship to food
      • Milk products (galactosaemia)
      • Fructose e.g. juices (hereditary fructose intolerance)
      • Protein (amino acid or organic acid disorders)
    • History of toxin ingestion – in toddlers or young children consider accidental ingestion of alcohol, oral hypoglycaemic agents (sulfonylureas), aspirin, beta blockers, or toxins
    • Increased glucose requirements, e.g. sepsis, shock, tumours, trauma
    • Past history
      • Neonatal history of hypoglycaemia
      • Episodes suggestive of hypoglycaemia e.g. undiagnosed seizure disorder
      • Previous gastric surgery, fundoplication (postprandial hypoglycaemia)
    • Family history
      • Consanguinity
      • Unexplained infant deaths (inborn errors of metabolism)
      • Hormonal deficiencies and hyperinsulinism

    Examination:

    • Altered conscious state and seizures
    • Fever or hypothermia
    • Finding related to underlying diagnosis
      • Hepatomegaly and/or hypotonia (inborn error of metabolism)
      • Poor growth and nutrition
      • Dysmorphic (syndrome)

    Management

    • First presentation or severe hypoglycaemia should be investigated
    • Infants <48hrs of age who respond appropriately to enteral feeds are unlikely to need extensive investigations
    • A capillary glucometer reading is unreliable at low readings; hence it is important to confirm that true (laboratory) BGL is <2.6mmol/l

    Investigations:

    • Venous/capillary blood gas
    • Diagnostic blood tests during the period of hypoglycaemia (either at the initial presentation or during an elective fast) prior to management

    Plasma glucose 1 or 3

    Ketones 1 or 3
    (Beta-hydroxybutyrate)

    Free fatty acids 1 (FFAs)

    Insulin & C-peptide 3

    Lactate 1 or 3

    Ammonia 2

    Cortisol 3

    Carnitine / Acylcarnitine 2,4

    Amino acids 2

    Electrolytes 2

    Liver Function Test 3

    Growth Hormone 3

    Minimum blood volume 5 mL
    Tubes Required:

    1. 3 x 0.5 mL fluoride oxalate
    2. 3 x 0.5 mL lithium heparin 
    3. 2 x 0.5 mL serum gel tube
    4. Newborn Screening Test (Guthrie) card - send air dried and in envelope, not in a plastic specimen bag

    All tests must go immediately to the laboratory on an ice pillow

    • Urine - first voided urine after hypoglycaemic episode, requesting glucose, ketones, reducing substances and amino and organic acids

    Treatment:

    • The aim of treatment is to return BGL to within the normal range (>3.9 mmol/L) through normal nutritional intake. See flow chart
      • Severe symptomatic hypoglycaemia should be corrected with an IV 10% dextrose bolus 2ml/kg or IM glucagon (Neonate: glucagon 0.03-0.1 mg/kg, <25kg give ½ vial (0.5 Units), <25kg give ½ vial (0.5 Units), >25kg give full vial (1.0 Units))
    • BGL should return to the normal range within 10-15 mins and remain so for 1 hour. Ideally, the child should start to feed and BGL should be rechecked within 30 mins
    • Persistent hypoglycaemia - consider consultation with Endocrinology and/or Metabolic specialist

    Hypoglycaemia -1

     Discharge requirements

    • A cause for hypoglycaemia must be known (or accelerated starvation assumed) prior to discharge
    • Neonates: BGL ≥2.6 for 3 consecutive normal feeds
    • Infants and older children: BGL >3 mmol/L at least 4 hours post feeds/meals
    • Accelerated starvation – parental education regarding prolonged starvation

    Consider consultation with local paediatric team when

    • Child is not responding to first line treatment of food, IV 10 % Dextrose bolus or IM glucagon
    • Neonates

    Consider transfer when

    • Child requiring multiple Dextrose boluses or Dextrose infusion
    • Child requiring care beyond the comfort level of the hospital

    For emergency advice and paediatric or neonatal ICU transfers, call the Paediatric Infant Perinatal Emergency Retrieval (PIPER) Service: 1300 137 650.

    Parent information sheet

    No KHI available - see Diabetic hypoglycaemia

    Interpretation of Test results

       Hypoglycaemia - 2

    Sample

     Test

    Interpretation

    Blood

    Glucose

    <2.6mmol/l - hypoglycaemia

    Ketones
    (Beta hydroxybutyrate )

    ↓ in:

    • Fatty acid oxidation defect
    • Hyperinsulinaemia

    Lactate

    ↑ in:

    • Metabolic liver disease
    • Glycogen storage disorders
    • Sepsis
    • Prolonged convulsion

    Free fatty acids

    Fatty acid oxidation defect

    Carnitine / acylcarnitine

    Fatty acid oxidation defect

    Ammonia

    ↑ in:

    • Organic acidaemias
    • Tyrosinaemia
    • Liver dysfunction
    • Hyperinsulinism-Hyperammonaemia Syndrome

    Cortisol

    ↓ in:

    • Hypoadrenalism
    • Hypopituitarism
    • ACTH deficiency

    Insulin & C-peptide

    Any detectable insulin in the presence of a BGL <2.6mmol/l is inappropriate

    Growth hormone

    ↓ in:

    • GH deficiency
    • Panhypopituitarism

    Amino acids

    Amino acid disorders

    Electrolytes

    Adrenal disorders

    Liver function tests

    Sepsis
    Liver disease
    Metabolic defects

    Urine

    Glucose

     

    Ketones

    ↓ in 

    • Fatty acid oxidation defect
    • Hyperinsulinaemia

    Reducing substances

    Galactosaemia 
    Fructosaemia


    Hypoglycaemia


    Last Updated November 2019

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