What initial investigations should I perform for a patient with suspected hyperkalaemia?

Initial investigations for suspected hyperkalaemia should include:

• Serum potassium measurement to confirm hyperkalaemia and assess severity.
• Serum creatinine and estimated glomerular filtration rate (eGFR) to evaluate kidney function and detect acute kidney injury, as impaired renal excretion is a common cause of hyperkalaemia.
• Assessment of other electrolytes, including sodium, calcium, and magnesium, since electrolyte imbalances often coexist and influence management.
• Electrocardiogram (ECG) to detect cardiac conduction abnormalities associated with hyperkalaemia, especially if the patient is symptomatic or potassium levels are significantly elevated.
• Review of medications that may contribute to hyperkalaemia, such as potassium-sparing diuretics, ACE inhibitors, ARBs, and NSAIDs.
• Clinical assessment for signs of hypovolaemia or other acute illnesses that may precipitate hyperkalaemia.

Additional investigations may be guided by clinical context, such as blood gas analysis if acidosis is suspected, or endocrine tests if adrenal insufficiency is considered.

Repeat serum potassium measurement is important to exclude spurious hyperkalaemia and to monitor trends.

These investigations help identify the underlying cause and guide urgent management to prevent life-threatening complications.