Critically elevated potassium in a 55-year-old female with chronic lymphocytic leukemia

Hyperkalemia in specimens from patients with chronic lymphocytic leukemia (CLL) may be due to tumor lysis syndrome (TLS) or specimen processing. This report describes a 55-year-old Caucasian woman with CLL who presented to an outside hospital with hyperkalemia and was transferred to a second hospital. Initial evaluation on the core laboratory chemistry analyzer (the VITROS 5600) and the ABL90 FLEX blood gas analyzer showed markedly elevated levels of potassium (K⁺). TLS was subsequently diagnosed, and dialysis was initiated. However, follow-up K⁺ measurements in whole blood (WB) yielded low levels that were unexpected after a single dialysis treatment. We then discovered that the initially elevated K⁺ level was from centrifuged plasma specimens and concluded that it indicated pseudohyperkalemia, likely from centrifugation. This case demonstrates that medical teams need be alert to potentially false K⁺ results in patients with elevated white blood cell counts. WB specimens are preferable, and steps to minimize trauma to the specimen and immediate analysis using blood gas instruments are recommended.