Paediatrics: Hypoglycaemia

2021-03-09 12:00 AM

Measurement of blood glucose using glucose reagent strips is unreliable. Use a blood glucose analyser or laboratory measurement.

Hypoglycaemia

  • Measurement of blood glucose using glucose reagent strips is unreliable. Use a blood glucose analyser or laboratory measurement.
  • The newborn period defined as <2.6mmol/L.
  • Blood glucose drops naturally in the first few hours after birth before normalising—newborns have an increased ability to utilize ketones/lactate for energy.
  • All infants should be encouraged to feed in the first hour if well enough.
  • At-risk groups for hypoglycaemia include; infant of the diabetic mother; <2500g or <3rd centile for weight; <37/40 gestation; maternal beta-blockers; birth asphyxia.
  • Check blood glucose in all infants who are unwell/lethargic/jittery.

Causes

  • Reduced glucose stores: preterm, IUGR, LBW, inborn errors of metabolism (IEM) (e.g. galactosaemia).
  • Increased glucose consumption: sepsis, hypothermia, perinatal hypoxia,polycythaemia, haemolytic disease, seizures.
  • Hyperinsulinism: maternal diabetes mellitus, BWS, pancreatic islet cell hyperplasia, transient.
  • Miscellaneous: maternal ß blockers, tissued or malfunctioning infusion.
  • Other rare causes: foetal alcohol syndrome, pituitary insufficiency, adrenal insufficiency.

Presentation

Commonly asymptomatic. Jitteriness, apnoea, poor feeding, drowsiness, seizures, cerebral irritability, hypotonia, macrosomia (if hyperinsulinism).

Investigation

Blood glucose should be measured in the first hour in all high-risk infants. Apart from regular blood glucose measurements, further investigation is not usually required if cause evident (e.g. IDM).

Suspicious patterns of hypoglycaemia meriting investigation include;

  • Recurrent hypoglycaemia in term infant despite functioning intravenous infusion (IVI) of glucose 10%.
  • Severe (<1mmol/L) and/or recurrent (>1) hypoglycaemia.
  • Symptomatic hypoglycaemia.
  • High glucose requirement (>8mg/kg/min).
  •  Hypoglycaemia and prolonged jaundice (panhypopituitarism) or sodium abnormalities (adrenal problems).
  • Hypoglycaemia with genital or midline abnormalities.

First-line tests (taken when hypoglycaemic):

  • Blood for glucose, insulin, growth hormone, cortisol, β-hydroxybutyrate, free fatty acids, amino acids (consider C-peptide, lactate, and ammonia).
  • Urine for urinalysis (ketones), amino and organic acids.
  • Further investigations as guided by results/clinical biochemist.

Prevention of hypoglycaemia in at-risk infants.

  • Adequate feed soon after birth (<1hr) and then at least 3-hourly.
  • Monitor blood glucose levels (pre-feed), keep warm, support feeding.

Prognosis

Profound/prolonged hypoglycaemia can cause neurological damage— the exact level/duration after which this may occur is unclear.

Treatment of hypoglycaemia

Symptomatic or severe hypoglycaemia 

(glucose<1.0mmol/L)

  • IV bolus 3–5mL/kg of glucose 10%
  • Follow with 10% glucose infusion IV (4–6mg/kg/min)

Asymptomatic 

(glucose <2.0mmol/L or 2.0–2.6mmol/L on 2 occasions)

  • Enterally fed infants:
  • inspect feed chart (frequency/volume, etc.)
  • if reluctant to feed—consider NGT
  • if not tolerating milk—consider IV
  • give early milk feed (consider larger volume)
  • monitor with pre-feed blood glucose levels
  • Infants on IV fluids:
  • check IV line is working
  • if glucose <1.0mmol/L—give bolus then increase infusion rate/ concentration
  • if glucose >1.0mmol/L—increase infusion rate/concentration

Resistant hypoglycaemia 

(glucose requirement >8mg/kg/min)

  • Seek specialist advice, as hyperinsulinism likely
  • Increase background glucose infusion (central IV access needed)
  • Glucagon 0.5mg IM can be given in emergency—rebound increased insulin secretion will occur
  • Treatment options include:

diazoxide (given with chlorothiazide to counteract fluid retention)

somatostatin (octreotide)

nifedipine

surgery (subtotal pancreatectomy)

  • Enteral feeding promotes normality. Aim to wean off IV as soon as able
  • High concentrations of glucose (>12.5%) require central IV access
  • Monitor plasma sodium if on IV fluids