Last reviewed by CRGH Renal Department 2012
Link to SLD potassium guidelines (Intranet)

Mild K+ < 3.5 mmol/L
Severe K+ <2.5 mmol/L

Common causes
Diuretics e.g. loop, thiazide
Other drugs e.g. insulin, salbutamol
Vomiting, diarrhoea
Metabolic alkalosis

Clinical Features
Muscle weakness
Cardiac arrhythmias
ECG – flattened T waves, ST depression, U waves (after T)

Serum EUC, Mg
Urine Na, K, creatinine
Urine K/Cr < 2 indicates extra renal loss with intact renal K+ handling.
Digoxin level (if patient on digoxin): note digoxin toxicity can occur with drug levels that are not high in hypokalaemia.

  1. Assess cause, ECG for arrhythmias, check serum Mg2+
  2. If the patient has just had haemodialysis repeat the K 4h later as serum K is usually very low after dialysis and does not reflect total body potassium
  3. Administer KCl intravenously if K+ < 3.0 mmol/L – always follow Sydney LHD guidelines
    • Maximum concentration in ward areas 40mmol per litre
    • Maximum rate in ward areas 10mmol per hour
  4. Oral potassium replacement
    • Slow K, Span K = 8mmol potassium per tablet
    • Chlorvescent = 14mmol potassium per tablet
  5. Correct magnesium if low
    • Hypokalaemia is often resistant to treatment until hypomagnesaemia is corrected
  6. Correct alkalosis: hypokalaemia is often resistent to treatment if alkalosis persists.
  7. Hypokalaemia will exacerbate digoxin toxicity, so correction of hypokalaemia should be expedited in the setting of digoxin use (even when digoxin levels are not especially elevated).
  8. Higher concentrations or rates of replacement require cardiac monitoring and central venous access and should always be discussed with a consultant