What is this test?
Potassium is essential for heart rhythm, nerves and muscles. Both high and low levels can be important and may result from kidney function, medicines, fluid loss or hormonal conditions.
Why might it be ordered?
- To investigate weakness, palpitations or an illness affecting fluid and electrolytes.
- To monitor kidney disease or medicines that raise or lower potassium.
What sample is needed?
A blood sample is required. The laboratory chooses the correct tube and handles the sample for this test.
How should you prepare?
Ask the laboratory whether you need to fast or attend at a particular time. Do not stop or change medicines or supplements unless your clinician tells you to.
How should you understand the result?
A haemolysed blood sample can falsely raise potassium and may need repeating. Markedly abnormal results or symptoms can require urgent ECG and medical assessment.
Sources and editorial status
This patient-facing text is an editorial draft. It should be approved by a laboratory physician before official publication.