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.
HYPOkalaemia
Treatment considerations
Plasma levels below 3.0 mmol/L may result in arrhythmias. Consider cardiac monitoring.
May be due to Total Body Deficit (where a 1 mmol/L drop in plasma level represents a total body loss of 200–400 mmol) or trans-cellular redistribution caused by a range of conditions and drugs (e.g. metabolic acidosis, diabetic ketoacidosis, insulin and salbutamol).
If resistant, check magnesium and replace if necessary, check for medicines which may decrease potassium (e.g. diuretics). Ensure potassium containing fluid is administered as necessary. See Guidelines for Prescribing Intravenous Fluids for Adults (PDF 364 kB).
All potassium containing infusions must be given via an infusion pump and also a burette if greater than 10 mmol.
Other drugs administered via Y-site may alter the infusion rate of potassium. Consider this and any incompatibilities when using this administration method.
Mild HYPOkalaemia
Mild hypokalaemia range is 3.5–3.1 mmoL/L
Treat with oral supplementation alone if oral route available. Administer Potassium chloride as either:
- effervescent tablets (e.g. Chlorvescent®) 1–2 tablets (14–28 mmol) two or three times daily
- slow release tablets 600 mg (e.g. Span K® or Duro K®) 2 tablets (16 mmol) twice daily. Up to 6 tablets (48 mmol) daily in divided doses may be required.
Moderate to severe HYPOkalaemia
Moderate hypokalaemia range is 3–2.5 mmol/L. Severe is less than 2.5 mmol/L.
Treat with both IV and oral supplementation where possible. Patients usually require at least 60–80 mmol potassium extra in the next 24 hours. This should be added to normal daily requirements.
Repeat plasma levels 4 hours after commencing treatment and review plan.
Maximum concentration peripherally is 40 mmol/L to prevent phlebitis.
Exceptions for treatment when:
- isotonic, premixed minibags (potassium 10 mmol in 100 mL) can be given peripherally. Minibags must be given via an infusion pump.
- maximum peripheral concentrations are exceeded. Administer through a central venous catheter.
Maximum rate
- If potassium level above 2.5 mmol/L = 10 mmol/hr
- With burette = 10 mmol/hr
- If potassium level below 2.5 mmol/L and with infusion pump = 20 mmol/hr
Note: If the above maximum rate is exceeded, cardiac monitoring, frequent blood monitoring and an infusion device are required. Administer through a large vein.
HYPOmagnesaemia
Treatment considerations
Hypomagnesaemia is common in hospitalised patients, especially the severely ill.
Magnesium may not be included with all electrolyte pathology requests. A specific request may be needed.
Beware of repeated doses in renal impairment.
IV magnesium is also used in conditions other than correction of electrolyte disturbance such as seizure prevention in pre-eclampsia. Check for its use prior to administration.
Mild or moderate hypomagnesaemia
Mild hypomagnesaemia range is 0.9–0.71 mmol/L. Moderate is 0.7–0.4 mmol/L.
Treat with oral supplementation of Magnesium aspartate tablets 500 mg (e.g. Magmin®) 1–2 tablets (1.54–3.08 mmol) twice daily. Up to 6 tablets (9.24 mmol) daily in divided doses may be required. Diarrhoea is a common side effect.
Severe or symptomatic hypomagnesaemia
Indicators or symptoms: Tremors, weakness, swallowing difficulties, cardiac arrhythmias or seizures.
Severe hypomagnesaemia is less than 0.4 mmol/L
Correct with intravenous magnesium:
- Magnesium Sulfate – each 5 mL ampoule contains 2.47 g magnesium sulfate equivalent to 10 mmol magnesium.
- Administer one to two ampoules (10–20 mmol) magnesium in 100 mL 0.9% sodium chloride over 1 hour. Can be given more rapidly in emergency situations.
- Review plasma levels or clinical symptoms within 6 to 12 hours.
HYPOnatraemia
Treatment considerations
Seek senior advice especially if severe or symptomatic such as drowsiness, headache, seizures.
Management requires careful assessment of fluid status and biochemical indices and is dependent on whether the disturbance is of an acute or chronic nature.
Venous blood gases are a more accurate and reliable indication of sodium and should be used for monitoring purposes.
Overcorrection can lead to permanent neurological injury.
Correction should occur slowly – generally no more than 8 mmol/L in 24 hours.
Faster or slower rates may be appropriate with senior advice.
In the event of overly rapid correction, seek specialist advice regarding the need for treatment to reverse or slow the rate of correction.
Mild or moderate hyponatraemia
Mild hyponatraemia range is 135–131 mmol/L. Moderate is 130–120 mmol/L
Assess fluid status.
- If hypovolaemic, correct intravascular deficit with 0.9% sodium chloride. See Guidelines for Prescribing Intravenous Fluids for Adults (PDF 364 kB).
- If euvolaemic or hypervolaemic, consider potential causes such as medicines (SSRIs, diuretics, antiepileptics), conditions associated with inappropriate ADH secretion or reduced effective circulating volume (cirrhosis, cardiac failure). Manage with fluid restriction.
Initial minimum monitoring levels is twice a day. More or less frequent monitoring may be required in certain circumstances such as when 3% sodium chloride is being used.
Severe or symptomatic hyponatraemia
Indicators or symptoms: Drowsiness, headache, seizures.
Severe hyponatraemia range is less than 120 mmol /L. If less than 120 mmol without symptoms consider managing as per mild or moderate.
Medical emergency – consider management in an intensive care/high dependency setting. Hypertonic saline and airway management may be indicated.
3% sodium chloride (hypertonic) requires careful consideration. Seek senior advice if required.
HYPOphosphataemia
Treatment considerations
Oral formulations are safe, effective and considerably cheaper than intravenous preparations.
Phosphate does not normally need replacement until less than 0.6 mmol/L except if alcoholism/withdrawal, malnutrition, re-feeding syndrome, receiving TPN, renal phosphate wasting, recovery from diabetic ketoacidosis or respiratory failure.
Sodium dihydrogen phosphate contains 10 mmol of phosphate and 10 mmol of sodium in a 10 mL ampoule. It contains zero potassium.
Mild to moderate hypophosphataemia
Mild hypophosphataemia range is 0.8–0.51 mmol/L. Moderate: 0.5–0.3 mmol/L
Observe and retest or treat with oral supplementation:
- Effervescent phosphate tablets 500 mg (e.g. Phosphate Sandoz) 1–2 tablets (16.1–32.2 mmol) up to three times a day. Diarrhoea is a common side effect.
- If not tolerated: one ampoule (10 mmol) of sodium dihydrogen phosphate in 250 mL of 0.9% sodium chloride infused slowly over 2 to 6 hours into a large vein.
Severe or symptomatic hypophosphataemia
Indicators or symptoms: haemolysis, respiratory failure, cardiac arrhythmias, weakness.
Severe hypophosphataemia range is less than 0.3 mmol/L
Correct with intravenous phosphate.
Administer one ampoule (10 mmol) of sodium dihydrogen phosphate in 250 mL of 0.9% sodium chloride over 2 to 6 hours into a large vein.
Monitor plasma phosphate, calcium levels and renal function every 12 to 24 hours.
In critically ill patients
- More concentrated solutions can be given, preferably via a central line. This may be one ampoule [10 mmol] of sodium dihydrogen phosphate in 100 mL of 0.9% sodium chloride. Administer at rates up to 10 mmol per hour, maximum of 40 mmol over 4 hours. Caution when giving repeat doses in renal impairment.
- Monitor plasma phosphate and calcium levels and renal function closely, for example every 1 to 2 hours. Monitor closely for clinical signs of hypocalcaemia.
HYPOcalcaemia
Treatment considerations
Remember: Ionised calcium is the physiologically relevant component of blood calcium and is available on a blood gas. Total calcium (even corrected for albumin) is an unreliable measure of functional calcium.
- If resistant to treatment, exclude hypomagnesaemia.
- Calcium gluconate contains 2.2 mmol of calcium in 10 mL.
- Extravasation of calcium can cause significant tissue necrosis.
- IV calcium is also used in conditions other than correction of electrolyte disturbance. Check use prior to administration.
Mild to moderate hypocalcaemia
Mild hypocalcaemia range is 2.15–1.91 mmol/L corrected. Moderate 1.9–1.5 mmol/L corrected.
Treat with oral supplementation of either:
- effervescent calcium tablets 1 g (Calsource®) 1–2 tablets (25–50 mmol) daily
- calcium 600 mg (e.g. Caltrate) 1–2 tablets (15–30 mmol) daily. Give with food.
Severe or symptomatic hypocalcaemia
Indicators or symptoms: Perioral/finger paraesthesia, seizures, tetany, positive Chvostek’s/Trousseau’s or patient is at high risk of becoming symptomatic (e.g. post-parathyroidectomy)
Severe hypocalcaemia range is less than 1.5 mmol/L corrected or 0.75 mmol/L IONISED
Correct with intravenous calcium gluconate.
- Administer two ampoules (4.4 mmol) in 100 mL 0.9% sodium chloride over
20 minutes. - Consider central venous catheter.
- A continuous infusion of calcium gluconate ten (10) ampoules (22 mmol) in 900 mL 0.9% sodium chloride at 50 mL/hr (adjusted for calcium levels) should be prescribed for the next 1 to 2 days.
Repeat plasma calcium level 4 hours after commencing treatment.