Hypokalaemia
Standard Treatment Guidelines and Essential Medicines List for South Africa, Hospital Level, Adults 2019 Edition
E87.6
DESCRIPTION
A serum potassium level <3.5 mmol/L.
Mild to moderate symptoms: muscle weakness (respiratory, and GIT muscles) and cramps.
Severe symptoms: rhabdomyolysis, paralysis, dysrhythmias, diaphragmatic weakness.
Signs of hypokalaemia: cardiac arrhythmias and/or ECG abnormalities (Prolonged QT interval, bradycardia).
Identify and treat/remove the cause: It is usually due to gastro-intestinal losses (diarrhoea) or kidney losses (diuretic therapy, hyperaldosteronism, vomiting).
MEDICINE TREATMENT
For chronic asymptomatic hypokalaemia, look for and manage the cause:
- Potassium chloride, oral, 600 mg, 1-2 tablets 8 hourly.
- Each 600 mg potassium chloride tablet contains 8 mmol of potassium chloride.
LoE:IVbxx - Titrate according to response to therapy.
- Maximum daily dose: 6 g (i.e.10 tablets per day in divided doses).
- Review potassium levels after 4 weeks.
- Each 600 mg potassium chloride tablet contains 8 mmol of potassium chloride.
OR
- Potassium chloride solution (1g/5ml) 10-30 mL daily in divided doses PO up to 6 g. (See Appendix IV: Extemporaneous preparations for the preparation formula for adults).
Note
Routine supplementation with potassium chloride in patients who are on diuretics is usually inappropriate. Co-administration of ACE-inhibitors and/or spironolactone counteracts the hypokalaemia from furosemide or thiazides. In patients that develop hypokalaemia while using potassium-sparing diuretics or ACEi/ARBs, consider underlying primary hyperaldosteronism.
For mild to moderate hypokalaemia in a non-vomiting patient. (Potassium level usually 3-3.4 mmol/L):
- Potassium chloride, oral, 1200 mg (2 tablets) 8 hourly.
- Each 600 mg potassium chloride tablet contains 8 mmol of potassium chloride.
- Titrate according to response to therapy.
- Maximum daily dose: 6 g (i.e.10 tablets per day in divided doses).
- Continue treatment until the serum potassium concentration is persistently above 3.5 mmol/L and symptoms or signs have resolved.
OR
- Potassium chloride solution (1g/5ml), oral, 10-30 mL daily in divided doses up to 6 g. (See Appendix IV: Extemporaneous preparations for the preparation formula for adults).
LoE:IVbxxi
For severe symptomatic hypokalaemia:
- Potassium chloride, IV by peripheral line, 40 mmol in 1 L of 0.9% or 0.45% sodium chloride, mixed thoroughly.
- Administer over 3 hours, or up to a maximum rate of 20 mmol per hour. Beware of volume overload (See Appendix II: Prescribing Information for Specific Medicines for individual dosing and monitoring for response and toxicity).
- Repeat as required, monitoring potassium serum levels after each replacement dose.
- One potassium chloride 15% 10 mL ampoule contains 20 mmol potassium.
- Maximum allowed daily dose of K+ is 3 mmol/kg/day (or 400 mmol/day).
LoE:IIIbxxii
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CAUTION
Potassium chloride ampoules must always be diluted before infusion.
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Reduce the rate of intravenous potassium repletion or change to oral therapy once the hypokalaemia is no longer severe. Continue treatment until the serum potassium concentration is persistently above 3.5 mmol/L and symptoms or signs have resolved.
Online calculator for calculating potassium deficit:
http://www.medicinehack.com/2011/07/hypokalemia-potassium-replacement.html
If not responding to therapy, check for hypomagnesaemia as low serum magnesium may potentiate potassium loss.
Standard Treatment Guidelines and Essential Medicines List for South Africa, Adult Hospital Level, 2020-2024_Version 1.0_17 October 2024
Chapter 7 Nephrology/Urological Disorders_7.2 Major Electrolyte Abnormalities_7.2.2 Hypokalaemia