When should I consider referring a patient with severe hypokalaemia (K+ < 3.0 mmol/L) to secondary care?

Consider referring a patient with severe hypokalaemia (potassium level less than 3.0 mmol/L) to secondary care if:

• The serum potassium is less than 2.5 mmol/L, which requires immediate hospital admission.
• The patient is symptomatic, especially with dysrhythmias, paralysis, respiratory failure, or severe weakness.
• There are clinical signs of hypovolaemia, thyrotoxic crisis, hypokalaemic periodic paralysis, metabolic acidosis/alkalosis, hyperosmolar hyperglycaemic state, or diabetic ketoacidosis.
• There is severe (less than 0.5 mmol/L) or symptomatic hypomagnesaemia.
• The patient has moderate hypokalaemia (2.5–2.9 mmol/L) but also has concurrent medical conditions that increase risk, such as cardiac disease (including heart failure), renal disease, or hepatic disease (e.g., cirrhosis).
• The cause of hypokalaemia is unclear or malignant disease is suspected, warranting specialist referral or urgent cancer pathway referral.
• The patient cannot tolerate oral potassium supplementation or requires intravenous potassium replacement.

For patients with potassium levels between 2.5 and 3.0 mmol/L who are asymptomatic and without significant comorbidities, primary care management with monitoring and treatment of underlying causes may be appropriate, with repeat potassium measurement after 2 weeks or sooner based on clinical judgement.

Referral urgency depends on clinical context and presence of risk factors or symptoms.

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