Replace potassium safely (≤ 10 mmol/h peripherally, ≤ 20 mmol/h centrally with monitoring), correct magnesium, and look for the cause (GI loss, diuretics, insulin, β-agonists, refeeding, RTA, hyperaldosteronism).
At the bedside
Timed steps- 1
Severity
AssessMild 3.0-3.4; severe < 2.5 or with ECG changes (U waves, ST depression, arrhythmia), weakness or paralysis, digoxin, or cardiac disease.
- 2
Oral if possible
ReplaceKCl 20-40 mmol 2-3 times daily.
- 3
IV
ReplacePeripheral up to 10 mmol/h (concentration ≤ 40 mmol/L); central with ECG monitoring up to 20 mmol/h. Each 10 mmol raises K+ ~0.1 mmol/L (less with ongoing losses).
- 4
Always check
MagnesiumHypomagnesaemia causes refractory hypokalaemia; give 2 g magnesium sulphate IV.
- 5
Urine K+
CauseUrine K+ < 20 mmol/day (or K/creatinine low) → GI/shift; high → renal loss (diuretics, vomiting, RTA, hyperaldosteronism).
Severe hypokalaemia
Potassium chloride
- Dose
- 20 mmol in 100 mL over 1 h; repeat with K+ checks
- Range
- 10–20 mmol/h
- Worked example
- K+ 2.4 with ectopics: 20 mmol/h centrally ×2, re-check; + 2 g MgSO4 over 30 min
Hypokalaemia
Step 1 of ~4
Decision: < 2.5, ECG changes, weakness or arrhythmia?
Based on Clase CM, Carrero JJ, Ellison DH, et al. Educational use; follow local protocol.
Evidence
- KDIGO 2020 controversies conference: consensus on potassium homeostasis; IV replacement rates reflect standard safety practice rather than trials.
🇮🇳 India notes
- Diarrhoeal illness and diuretics are the commonest causes; hypokalaemic paralysis presents frequently to Indian emergency departments, including distal RTA and thyrotoxic periodic paralysis.
References
Test yourself
Module quiz · score 70% to complete the module
Educational reference for trained clinicians. Check doses against your hospital protocol and the patient in front of you.