Pseudohyperkalaemia in Chronic Lymphocytic Leukaemia: A Case Series of Three Avoidable Escalations

Abstract

Pseudohyperkalaemia -- a spuriously elevated serum potassium arising from potassium release during or after sample collection
rather than from a true elevation in vivo -- is a recognised but under-considered phenomenon in chronic lymphocytic leukaemia
(CLL), where a very high circulating lymphocyte count makes cell fragility during clotting or prolonged storage a more prominent
source of in vitro potassium release than in the general population. We report three cases of CLL patients with markedly elevated
serum potassium results that prompted urgent clinical escalation -- including one emergency department presentation for cardiac
monitoring -- before pseudohyperkalaemia was identified via a simultaneous plasma sample showing a normal potassium result.
We describe the distinguishing clues in each case and propose a practical laboratory pathway for a markedly elevated potassium
result in a patient with a high circulating lymphocyte count.