See also
Intravenous fluids
Electrolyte
abnormalities
Hyperkalaemia
Diabetic Ketoacidosis (DKA)
Key points
- Oral/enteral is the preferred route of potassium administration
- Intravenous potassium replacement carries risks of inadvertent hyperkalaemia, fluid overload, and peripheral vein extravasation/thrombophlebitis. Rapid intravenous administration or overdose may cause cardiac arrest
- Monitoring of clinical/fluid status and electrolytes is important in children receiving potassium supplementation
- 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
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).
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.
Last Updated April, 2019