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Abstract: FR-PO674

Is This the Real Lyse? Is This Just Fantasy? Pseudohyperkalemia with Concurrent Tumor Lysis Syndrome in Extreme Leukocytosis

Session Information

Category: Trainee Case Report

  • 1500 Onco-Nephrology

Authors

  • Tan, Hui Zhuan, Singapore General Hospital, Singapore, Singapore
  • Kaushik, Manish, Singapore General Hospital, Singapore, Singapore
  • Choo Chon Jun, Jason, Singapore General Hospital, Singapore, Singapore
Introduction

Hyperkalemia is a potentially dangerous electrolyte imbalance encountered in hematological malignancies, often seen in tumor lysis syndrome (TLS) and renal failure. It is increasingly recognised that potassium can be spuriously elevated in severe leucocytosis.

Case Description

A 74-year-old Chinese gentleman presented to the emergency room with 3 days of giddiness and was diagnosed with Chronic Myeloid Leukemia with blast crisis. Notable serum laboratory results included marked leucocytosis of 710x 109/L, platelets of 680x109/L, hemoglobin of 5.5 g/dL, creatinine of 289 µmol/L, potassium of 7.2 mmol/L (unlysed), phosphate of 1.69 mmol/L and markedly elevated uric acid and lactate dehydrogenase levels of 1572 µmol/L and 10,761 U/L respectively. Electrolyte abnormalities were attributed to spontaneous TLS with KDIGO Stage 3 acute kidney injury (AKI). Emergent medical therapy was instituted with insulin/dextrose, intravenous hydration and hydroxyurea. Rasburicase was withheld pending glucose-6-phosphate dehydrogenase status. Urgent renal consult was obtained for the consideration of renal replacement therapy (RRT) in view of oliguria. Simultaneous serum and whole blood potassium sample analysed via direct potentiometry subsequently revealed significantly discordant results of >8.0mmol/L and 4.7mmol/L respectively. Pseudohyperkalemia was suspected and corroborated by the absence of typical hyperkalemia changes on electrocardiographs. Serial paired samples yielded similar results, confirming the diagnosis. Despite this, decision was made to proceed with RRT in view of anuric AKI, ongoing TLS in the setting of large tumor burden, with anticipated delay of rasburicase administration and definitive chemotherapy.

Discussion

Pseudohyperkalemia occurring with extreme leucocytosis is multifactorial. It results from lysis of fragile leukocytes during clotting, compounded by mechanical stress during venepuncture, pneumatic transport and centrifugation. This phenomenon may go unrecognised in the setting of concurrent TLS and high index of suspicion is required. Diagnosis can be made by evaluating samples with direct potentiometry or sent in heparin-lithium tubes. While management of isolated pseudohyperkalemia in the absence of AKI is conservative, threshold to initiate dialysis should be lowered if there is concurrent TLS and oliguria.