General prescribing advice

Electrolyte disturbances that are difficult to treat often indicate significant disease or coexisting ion disturbances — seek advice.

Unit-specific protocols for electrolyte disturbances take precedence over these guidelines. Dialysis patients often present unique challenges.

Where several treatment options are provided, undertake in a stepwise fashion not concurrently. Sufficient time between interventions should elapse to ensure maximal response has occurred.

Rapid administration of electrolytes or correction of severe derangements may result in cardiac arrhythmias — consider cardiac monitoring.

Electrolyte solutions are incompatible with blood products, some medicines and often each other. Seek advice before mixing together in an infusion or giving simultaneously via the same IV line.

All electrolyte solutions should be administered via a pump with dose error reduction software.

Consider contributing factors including medicines and nutritional products. If asymptomatic consider if treatment is needed — use clinical judgement.

HYPERkalaemia

Treatment considerations

Consider clinical situation, if asymptomatic confirm level. Consider possibility of sample haemolysis.

Hyperkalaemia is more sinister in setting of an acute rapid rise rather than chronic renal failure and in patients with pre-existing heart failure.

Mild to moderate or asymptomatic hyperkalaemia

Mild range is 5.2–5.9 mmol/L. Moderate range 6.0–6.5 mmol/L.

  • Check ECG.
  • Place on a low potassium diet.
  • Review medicines.
  • Monitor potassium levels every 12 hours (moderate) to 24 hours (mild).

Long-term management

Review for possible reversible causes of hyperkalaemia. Examples of possible causes may include haemolysis, acidosis, renal impairment.

Severe or symptomatic hyperkalaemia

Severe hyperkalaemia is more than 6.5 mmol/L

Indicators or symptoms: muscular weakness and/or ECG changes (e.g. peaked T waves)

Institute continuous ECG monitoring.

Seek senior advice and consider the following points:

Protect the heart

  • If ECG abnormalities are present – calcium gluconate one ampoule (2.2 mmol of calcium) IV via a central vein or slowly over 2 to 3 minutes into a large vein.
  • If ECG does not normalise within 10 minutes, dose may be repeated (to a total of 0.1 mmol/kg).

Reduce serum potassium level

Reducing serum potassium with insulin should only be considered if severe (more than 6.5 mmol/L) or symptomatic. Hypoglycaemia may occur many hours after administration of insulin.

Consider administering one or a combination of:

  • Glucose and insulin – glucose 50% 50 mL with 5–10 units of insulin (e.g. Actrapid® or NovoRapid®) IV over 5 minutes.
    • Consider 5 units in patients under 50 kg or with chronic kidney disease (CKD stage 4 and 5).
    • Monitor BGL every hour minimum in the first six hours.
    • Consider continuous glucose infusion to prevent hypoglycaemia.
  • Inhaled salbutamol – nebulised salbutamol 10 mg (2 of the 5 mg/2.5 mL nebules) OR metered dose inhaler 1200 micrograms (12 puffs) via spacer
  • sodium bicarbonate – 8.4% 50 mL IV over 5–15 minutes if metabolic acidosis is present. In an emergency this can be administered by a peripheral line with caution.

Remove potassium from the body

Consider administering one or a combination of:

  • Resonium-A® – give 15–30 g orally up to four times daily or 60 g as a retention enema daily
  • Dialysis – urgent dialysis may be required.

Review medicines

Withhold any potassium retaining drugs such as ACE inhibitors, angiotensin receptor antagonists, potassium sparing diuretics, trimethoprim, β-blockers, NSAIDs, digoxin or potassium containing products.

Monitor potassium level hourly.

HYPERcalcaemia

Treatment consideration

Hypercalcaemia is most commonly due to primary hyperparathyroidism OR hypercalcaemia associated with malignancy.

Mild hypercalcaemia

Mild range is 2.55–2.9 mmol/L.

Moderate to severe or symptomatic hypercalcaemia

Moderate range is 3.0–3.2 mmol/L. Severe range exceeds more than 3.2 mmol/L corrected.

Indicators or symptoms: lethargy, coma, ECG changes (shortened QT interval)

Seek senior advice if:

  • rehydration – intravenous sodium chloride 0.9%. Volume infused should be sufficient to maintain a urine output greater than 60 mL/hr.
  • Bisphosphonate therapy with either zoledronic acid or pamidronate may be indicated.

Long-term management

Review for possible causes including:

  • diet or supplements (vitamin D or calcium)
  • sarcoidosis and other granulomatous disease
  • drug causes such as calcitriol excess or thiazide diuretics
  • spinal cord injury and/or immobility.

HYPERnatraemia

Treatment considerations

Seek senior advice especially if severe or symptomatic.

Oral/enteral fluid replacement with water is safest.

Hypernatraemia is often due to fluid deficit. Correct haemodynamic instability first with sodium chloride 0.9%.

Intravenous fluids without added sodium (generally glucose 5%) may be needed.

In the setting of hyperglycaemia the preferred fluid of choice is sodium chloride 0.9%.

Mild to moderate hypernatraemia

Mild to moderate hypernatraemia range is 145–159 mmol/L

Severe or symptomatic hypernatraemia

Indicators or symptoms: hyperthermia, delirium, seizures, coma

Severe hypernatraemia range is more than 160 mmol/L

Medical emergency

Consider management in an intensive care/high dependency setting.


To prevent permanent neurological injury, serum sodium concentration should be reduced by not more than:

  • 0.5 mmol/L per hour
  • 10 mmol/L in 24 hours.

Monitor every 4 hours in the first 24 hours.

HYPERmagnesaemia

Treatment considerations

May be deliberate in pregnancy. Magnesium is used to treat/prevent eclampsia/severe pre-eclampsia. Always contact Obstetrician.

Severe or symptomatic hypermagnesaemia

Indicators or symptoms: Loss of deep tendon reflexes, respiratory depression, paralysis, reduced consciousness)

Severe hypermagnesaemia range is more than 2.5 mmol/L

Intravenous calcium gluconate provides immediate but transient antagonism of toxic effects.

Protect the heart

One ampoule (2.2 mmol) of calcium gluconate in 0.9% sodium chloride should be administered over 5 minutes. Repeat if necessary.

Reduce serum magnesium level

  • Kidney excretion should be promoted with intravenous sodium chloride 0.9%, aiming for a urine output of at least 60 mL per hour.
  • If urine output can’t be achieved through above method, intravenous frusemide can be added.
  • Dialysis may be needed.
  • Review diet and medicines for antacids, enemas, supplements and lithium.

Last updated: 6 May 2026