Defined as serum K <3.5mmol/L

• Moderate 2.5 - 3
• Severe <2.5

Causes

• Increased losses -

  • GI - D&V
  • Renal - Diabetic, Mineralocorticoid excess, reduced Mg

• Redistribution into cells

  • Metabolic alkalosis
  • Insulin
  • Refeeding syndrome
  • B-agonists - salbutamol

  Hypokalaemia with alkalosis

  • vomiting
  • thiazide and loop diuretics
  • Cushing's syndrome
  • Conn's syndrome (primary hyperaldosteronism)

  Hypokalaemia with acidosis

  • diarrhoea
  • renal tubular acidosis
  • acetazolamide
  • partially treated diabetic ketoacidosis

Relationship with hypomagnasaemia

Magnesium levels should also be checked as concomitant hypomagnasaemia increases the risk of arrhythmia.

Hypomagnasaemia can also cause hypokalaemia

Clinical features

• muscle weakness, hypotonia
• hypokalaemia predisposes patients to digoxin toxicity - care should be taken if patients are also on diuretics

Investigations

U and Es:

• <3.5mmol/L

ECG: