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Pseudohyperkalaemia Haemolysis — ESENeph MCQ

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EasyElectrolyte DisordersPseudohyperkalaemia HaemolysisESENeph

A 58-year-old man with CKD G4 on Ramipril has a potassium of 5.6 mmol/L. His serum sample was difficult to obtain – the phlebotomist struggled and the tourniquet was left on for several minutes. The lab notes the sample was haemolysed. Is this a true result?

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Correct answer: E — Pseudohyperkalaemia should be suspected – haemolysis from difficult venepuncture releases intracellular potassium; repeat the sample with careful technique before acting

Pseudohyperkalaemia occurs when potassium is released from cells during or after blood sampling. Common causes include haemolysis (from difficult venepuncture, tight tourniquet, small-bore needles), thrombocytosis (potassium release from platelets during clotting), and leukocytosis. A haemolysed sample with a borderline potassium elevation in a patient without ECG changes or clinical deterioration should be repeated with careful venepuncture technique before initiating treatment. Unnecessary treatment for pseudohyperkalaemia is common and avoidable.

Reference: UK Renal Association 2020 – Hyperkalaemia; Wiedemann and Lam 1987