Monitoring

Hospitalised patients

Patients with severe hyperkalaemia should be frequently assessed for abnormal vital signs, rebound hyperkalaemia, and adverse effects of drugs administered. Patients with haemodynamic instability or persistent new ECG abnormality and those with persistent hyperkalaemia or treatment that did not include elimination of potassium should be admitted for further evaluation.[2]​ These patients should have close follow-up after discharge, usually within 24-48 hours.[2]

Patients in the community

Think Kidneys in the UK has suggested guidance on repeat testing after a hyperkalaemic episode that occurs in the community, based on the level of hyperkalaemia and clinical context.[1][103]

  • In patients with mild hyperkalaemia (serum potassium 5.5 to 5.9 mmol/L [5.5 to 5.9 mEq/L]), a repeat test is recommended within 3 days if the result was unexpected, or as soon as feasible if the patient is clinically stable.

  • In patients with moderate hyperkalaemia (serum potassium 6.0 to 6.4 mmol/LmEq/L [6.0 to 6.4 mEq/L]), a repeat test is recommended within 1 working day if detected on a routine check in a stable patient, but referral to hospital should be considered if clinically unwell or if acute kidney injury (AKI) is present.

  • Patients with severe hyperkalaemia (serum potassium ≥6.5 mmol/L [≥6.5 mEq/L]) should be referred to hospital on an urgent basis for immediate assessment and treatment.

Routine monitoring in patients at risk of hyperkalaemia

Routine potassium monitoring is necessary for patients with risk factors for hyperkalaemia (including patients with kidney dysfunction, diabetes, heart failure, liver disease, or distal tubule defects, or patients on renin-angiotensin-aldosterone system inhibitors [RAASi] or aldosterone antagonists), with blood monitoring 2-4 times annually, depending on the patient’s kidney function and level of proteinuria.[1]

Assess potassium levels and renal function before initiation of RAASi in all patients.[1][104]​​​​ These drugs should be used with caution when the baseline serum potassium is >5.0 mmol/L (>5.0 mEq/L) or if the patient has an estimated glomerular filtration rate (eGFR) <30 mL/minute/1.73 m² (a dose reduction may be necessary with some drugs).[1] Serum potassium concentrations should be assessed 7-10 days after starting RAASi, and after increasing the dose.[4][104]​​​​​ Recommendations may vary between drugs within this class and between geographical locations; consult your local drug formulary for more information.

Assess potassium levels and renal function before initiation of aldosterone antagonists in all patients.[1]​​​ Aldosterone antagonists should be avoided when the baseline serum potassium is >5.0 mmol/L (>5.0 mEq/L) or the eGFR is <30 mL/minute/1.73 m².[1] Serum potassium concentrations should be assessed 7 days after starting aldosterone antagonists or after increasing the dose, then monthly for the first 3 months, 3-monthly for the first year, and then at 4-monthly intervals.[1] Recommendations may vary between drugs within this class and between geographical locations; consult your local drug formulary for more information.

The frequency of ongoing monitoring of potassium in other at-risk groups is not well defined.

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