• ABCDE approach and NEWS system
• Comprehensive medical and drug history and clinical examination to determine the cause of hyperkalaemia

Symptoms and signs

• Frequently none, or non-specific neuromuscular symptoms
• Muscular weakness may occur if blood K⁺ >7.0 mmol/L
• Cardiac arrest without warning
• ECG changes (see Treatment)

Investigations

• In emergency, measure K⁺ on a point-of-care blood gas analyser and initiate treatment whilst awaiting the results from a laboratory plasma sample (green top; lithium heparin)
• HCO₃^- in venous blood (or from blood gases, if indicated for other reasons) and lactate
• If serum K⁺ ≥6.0, urgent 12-lead ECG. If ECG abnormal, or rapid rise in K⁺ levels and in patients with plasma K⁺ ≥6.5 mmol/L, continuous 3 lead cardiac monitoring; ideally in a high-dependency setting

Common Causes

• Artefact: release from blood cells (e.g. during clotting, blood dyscrasias, haemolysis, delayed centrifugation of sample for >2 hr)
• Low molecular weight heparin
• Failure of excretion: renal failure, mineralocorticoid deficiency, drugs e.g. spironolactone, amiloride (potassium sparing diuretics), ACE inhibitors (~prils), angiotensin II blockers (~sartans), aliskiren, NSAIDs, ciclosporin, tacrolimus
• Release from cell: severe tissue damage, acidosis (consider DKA, lactic acidosis)
• Excess ingestion or supplementation

• If refractory shock/other organ failure or cause not known, seek advice from ITU and or renal team
• Protect the heart and lower K⁺. For guidance follow algorithm below
• Treat the underlying cause