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Key messages

  • Electrolyte status after birth reflects maternal status and should only be used as a baseline.
  • Infant with electrolyte abnormalities may be asymptomatic.
  • Abnormal results in asymptomatic infants may be due to sampling or laboratory error and repeat treatment is advised.
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Please note that all guidance is currently under review and some may be out of date. We recommend that you also refer to more contemporaneous evidence in the interim.

Apart from acid-base balance, electrolyte levels immediately after birth reflect maternal electrolyte status and are therefore only useful as a baseline. The exception might be a mother who has been water overloaded during labour causing both her and the fetus to become hyponatraemic. In some cases the infant may be symptomatic (seizures) and require treatment. Issues to note:

  • An unexpectedly abnormal result in a well, asymptomatic infant is most likely to be due to sampling or laboratory error. In this situation, it always advisable to repeat the test before embarking upon a potentially risky correction.
  • As with all interventions, it is wise to consider the risks vs benefits of correcting any electrolyte disturbance.
  • Refer to the section on normal laboratory values for definitions.

Guide to treatment of electrolyte abnormalities

These recommendations are a guide only.

Hypocalcaemia

Guide to interventions:

  • 1.5 mL x wt(kg) of 10 per cent calcium gluconate in maintenance intravenous fluid over four hours
  • 1 mL of 10 per cent calcium gluconate contains 0.2 mmol calcium
  • only indicated if the baby is symptomatic
  • side effects include
    • reduced IV half life
    • risk of IV burn
  • consider hypomagnesaemia if recalcitrant hypocalcaemia.

Hyponatraemia

Guide to interventions:

  • 0.18 x deficit (from lower limit of normal for age) mL x wt(kg) of 20 per cent sodium chloride over six hours (12 hours if < 120 mmol/L as rapid or over correction can cause neurological complications)
  • 1 mL of 20 per cent sodium chloride contains 3.42 mmol sodium
  • consider cause of hyponatraemia
    • urinary losses - check urinary sodium
    • GIT losses
    • inadequate intake of sodium
    • excessive intake of water
    • SIADH (rare in very premature infants).

Hypokalaemia

Guide to interventions:

  • 1.2 mL x wt(kg) of 15 per cent potassium chloride over six hours
  • do not exceed 0.4 mmol/kg/hr
  • 1 mL of 15 per cent potassium chloride contains 2 mmol potassium
  • consider cause of hypokalaemia
    • resolving/recent metabolic acidosis
    • diuretics, particularly frusemide
  • Note: true hypokalaemia may be missed if haemolysis occurs during sampling. Capillary specimens are usually haemolysed to a greater or lesser degree.

Hypomagnesaemia

Guide to interventions:

  • 0.2 mL x wt (kg) 50 per cent MgSO4, diluted to 20 per cent IV slowly (may be arrhythmogenic). IMI administration, although painful, is an alternative if there is no intravenous cannula in situ
  • do not exceed 0.75 mL/minute
  • 1 mL of 50 per cent magnesium sulphate contains 2 mmol magnesium
  • consider with
    • recalcitrant hypocalcaemia
    • PPHN
    • seizures
  • may cause hypotension if given too quickly.

Metabolic acidosis (sodium bicarbonate)

Guide to interventions:

  • 0.25 x base deficit x wt(kg) of 8.4 per cent NaHCO3, diluted 1:1 with H2O, given slowly over 30-60 minutes
  • consider half correction to prevent rapid changes in pH
  • 1 ml 8.4 per cent NaHCO3 contains 1 mmol bicarbonate
  • do not dilute with 10 per cent dextrose as this:
    • increases osmolality and risk of IVH
    • is unnecessary
    • disturbs glucose homeostasis
  • consider if B.E. < -8.0, although pointless if pCO2 not controlled
  • consider and treat underlying cause which could be:
    • hypoxia 
    • hypotension 
    • poor perfusion
    • patent ductus arteriosus
    • sepsis.

If chronic acidosis, consider renal tubular cause and check urine pH at time of acidosis (if acidotic, should be <=5).

More information

Other reading

  • Walter JH. Metabolic acidosis in newborn infants. Arch Dis Child 1992;67:767-9
  • Modi N. Sodium intake and preterm babies. Arch Dis Child 1993;69:87-91
  • Herin P, Zetterstrom. Sodium, potassium and chloride needs in low-birth-weight infants. Acta Paediatr 1994; Suppl 405:43-8
  • Trachtam H. Sodium and water homeostasis. Pediatr Clin North Am 1995;42:1343-43
  • Taeusch HW, Ballard RA (Eds). Avery's Diseases of the Newborn 7th Ed. W.B. Saunders Company, Philadelphia. 1998

Get in touch

Centre of Clinical Excellence - Women and Children
Safer Care Victoria

Version history

First published: July 2014

Last reviewed: October 2018

Review by: December 2018

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Page last updated: 17 Feb 2021

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