Treatment of Moderate to Severe Hypokalemia When Serum Potassium Falls Below 2.5 mmol/L in Adults Aged 16 and Over

This protocol covers the structured inpatient management of adult patients aged 16 years and over with a confirmed serum potassium level below 2.5 mmol/L — the threshold for severe hypokalaemia requiring prompt clinical action.

Clinical Scenario

Serum Potassium < 2.5 mmol/L

Adult patient aged 16 years or over with severe hypokalaemia defined by a serum potassium below 2.5 mmol/L. The protocol applies specifically to this age group and at this depth of depletion.

Treatment Approach

At this severity, intravenous potassium replacement in a hospital setting is required. The protocol specifies infusion administered through a peripheral vein under consultant direction, using an infusion pump, with mandatory continuous cardiac monitoring throughout. The complete regimen — covering concentration thresholds, rate limits, timing of reassessment, and transition criteria — is set out in the full structured protocol.

Treatment Goal

Serum potassium rises above 2.9 mmol/L, confirmed by repeat measurement. Monitoring continues at least daily until this target is achieved.

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References

Severe <2.5 mmol/L
This guideline does not apply to patients under the age of 16.
When hypokalaemia is severe with marked clinical features, or unresponsive to oral therapy, potassium must be replaced intravenously.
Give via a large vein under the direction of a consultant.
Concentrated infusion solutions containing more than 20mmol/500mL (0.04mmol in 1mL) should be given using an infusion pump.
Continuous ECG monitoring is mandatory for infusion rates of 20mmol/hour, and for concentrations of 40mmol/500mL or higher.
Maximum of 2 hours duration then recheck potassium levels.
Monitor serum potassium following initial therapy, and then at least daily until serum potassium >2.9mmol/L then manage as above.

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