See also

Intravenous fluids

Electrolyte abnormalities 
Hyperkalaemia
Diabetic Ketoacidosis (DKA)

Key points

1. Oral/enteral is the preferred route of potassium administration
2. Intravenous potassium replacement carries risks of inadvertent hyperkalaemia, fluid overload, and peripheral vein extravasation/thrombophlebitis. Rapid intravenous administration or overdose may cause cardiac arrest 
3. Monitoring of clinical/fluid status and electrolytes is important in children receiving potassium supplementation 
4. Specialist advice should be sought for critical or symptomatic hypokalaemia
   

Background

Hypokalaemia is defined as a plasma potassium level less than 3.5 mmol/L. 

Serum potassium (mmol/L)	Severity
3.0 - 3.4	Mild
2.5 - 3.0	Moderate
2.0 - 2.4	Severe
<2.0	Critical

The goals of treating hypokalaemia are to:

• prevent life threatening complications: arrhythmias, paralysis, rhabdomyolysis, diaphragmatic weakness
• replace potassium deficit
• correct the underlying cause
  

Causes 

Decreased intake	Increased losses	Transcellular shifts	Medicines	Spurious
Illness   Fasting   Prolonged IV fluids not containing potassium   Eating disorder	Gastrointestinal Vomiting Diarrhoea Fistula   Renal Diuretics Osmotic diuresis Aldosterone excess Mineralocorticoid excess Congenital disorders Renal artery stenosis	Alkalosis   Hypomagnesaemia   Hypernatraemia   Glucose/insulin infusion   Diabetic ketoacidosis   Refeeding syndrome	Loop diuretics (eg  frusemide) Thiazide diuretics   Amphotericin Cisplatin   Insulin Salbutamol Adrenaline	Sampling error Recent line flush IV fluids near sampling site

Prevention

In general, children eating a variety of foods will meet their daily potassium requirements.

Consider the addition of potassium to maintenance fluids (see Intravenous Fluids) for children who are:

• nil by mouth/enterally for prolonged periods (particularly if increased losses)
• at risk of hypokalaemia (see table above, Causes) 
  

Assessment 

History and examination

Identify underlying cause and correct where possible

Assess for signs/symptoms of hypokalaemia

• muscle weakness, cramps, paralysis
• hyporeflexia
• constipation, ileus
• lethargy, confusion
• rhabdomyolysis (rare)

Assess fluid status as a baseline 

Investigations

Consider:

• repeat electrolytes to verify the initial result

Note: serum potassium level can be falsely elevated in haemolysed/finger prick samples, so a venous sample should be taken if clinical suspicion of hypokalaemia

• baseline renal function
• blood gas if concerns regarding acid-base status
• serum magnesium level, especially if hypokalaemia is refractory to treatment (hypomagnesaemia promotes potassium wasting) 
  

Perform ECG if signs/symptoms of hypokalaemia, risk of cardiac arrhythmia, or serum potassium <3 mmol/L.

• Look for wide flat T waves, ST depression, T wave inversion, tall wide P waves, prolonged PR segment, U waves, apparent prolonged QT (fusion of T and U waves), prolonged QRS, arrhythmia. 
  

Management

Replacement

Potassium replacement is indicated if:

• serum potassium <3.0 mmol/L or
• serum potassium <3.5 mmol/L with symptoms/signs/ECG changes

If serum potassium is 3.0 mmol/L - 3.4 mmol/L in a well child, it is reasonable to either:

• monitor electrolytes,
• increase maintenance potassium dose, or
• replace potassium depending on the clinical situation  

In children with stable haemodynamics and no ECG changes, aim for a gradual correction over 24-48 hours.

Correct serum magnesium as necessary.

Choice of dosing route 

Oral/enteral is the preferred route of administration

• Oral potassium is well absorbed from the gastrointestinal tract.
• Best taken with or soon after food to reduce gastrointestinal irritation.
  

Consider intravenous replacement if:

• child is unable to tolerate oral medication,
• serum potassium <2.5 mmol/L, or
• ECG changes present
  

Oral/enteral dosing

Dosage:

Acute replacement dose	1 - 2 mmol/kg/dose orally (maximum 20 mmol per dose) Dose may be repeated, after checking serum potassium level, to a maximum of 5 mmol/kg/DAY (maximum daily dose 50 mmol)
Maintenance dose (if required)	2 - 5 mmol/kg/DAY orally in divided doses (maximum 20 mmol per dose)

Medication Forms: 

	Potassium content	Notes
Potassium Chloride Oral Mixture (where available)	1.33 mmol/mL	Rapid absorption Expected serum potassium rise after approximately 2 hours
Effervescent tablet eg Chlorvescent®	14 mmol per tablet	Rapid absorption Ensure tablets are completely dissolved before administration Expected serum potassium rise after approximately 2 hours
Controlled release enteric coated eg Slow K®	8 mmol per tablet	Slow release, delayed absorption Use for mild or chronic hypokalaemia Tablets must be swallowed whole Expected serum potassium rise after approximately 4 hours

 

Repeat serum potassium level: For acute oral potassium replacement, consider repeat serum potassium level at a time interval guided by the clinical context and the expected serum potassium rise. 

Intravenous dosing

Dosage

• Rapid intravenous administration or overdose may cause cardiac arrest. Administer via an infusion pump using Dose Error Reduction Software (DERS) where available.  
• Include all sources of potassium when calculating replacement doses and infusion rates (eg additives to maintenance fluids, Parenteral Nutrition, oral/enteral supplements).
• Potassium-containing fluids, including parenteral nutrition, may need to be paused during acute replacement to ensure the maximum rate of potassium administration is not exceeded.

Ward Area (specific to RCH)	Acute replacement dose	Maintenance dose (if required)	ECG monitoring required	Repeat serum potassium level	Notes on serum potassium level monitoring
General ward	0.2 mmol/kg/hour for 3 hours (maximum 10 mmol/hour)   Note: Dose likely to require intravenous fluid rate greater than maintenance fluid rate	1 - 4 mmol/kg/day (maximum 10 mmol/hour)   Doses greater than 4 mmol/kg/day should be discussed with a Senior Clinician or local retrieval service	Only required if serum potassium <3 mmol/L or risk of cardiac arrhythmia	1 hour after replacement completion	Check serum potassium level before administering further potassium   Continue to monitor serum potassium levels at a frequency guided by the response and clinical situation
Critical Care Areas	0.4 mmol/kg/hour for 1 - 2 hours (maximum 20 mmol/hour)   Note: Dose likely to require concentrated potassium infusion (see below) and central line		Yes	1 hour after replacement commencement AND 1 hour after replacement completion

 

For children with DKA: please refer to Diabetic Ketoacidosis (DKA)

Administration

Intravenous Access	Potassium concentration	Dosage form	Notes
Peripheral line	Maximum 60 mmol/L*	Use premixed fluid bags where possible (various concentrations available)     When adding potassium chloride to an IV fluid bag, mix well by inverting the bag at least 10 times Clearly label all bags, syringes, pumps and lines that contain potassium to avoid inadvertent flushing	Monitor intravenous access site for signs of extravasation or thrombophlebitis
Central line	Concentrations >60 mmol/L must be given via a central line only	There are a number of concentrated potassium formulations available   Only administer in areas where there is a clear protocol for administration and monitoring   Contact local retrieval service for further advice	Use should be approved by a Senior Clinician   ECG monitoring required

* The premixed product 10 mmol potassium chloride in 100mL 0.29% sodium chloride can be administered via a peripheral line as the product is isotonic due to the reduced sodium content

Monitoring

Ensure regular monitoring of:

• vital signs
• clinical and fluid status including urine output
• any signs of hyperkalaemia (see Hyperkalaemia)
• IV access site
  

Consider consultation with local Paediatric service when

• the child requires admission
• the child requires potassium replacement  
  

Consider consultation with local retrieval service when

• serum potassium <2.0
• symptomatic hypokalaemia
• ECG changes
• renal impairment (including oliguria or high/rising creatinine)
• risk cardiovascular arrhythmia
• fluid overload
• neonates
• complex children with renal, oncological, haematological, cardiac, endocrinological, and metabolic conditions 
  

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