Reverse Pseudohyperkalemia in a Leukemic Patient

Abstract

A 49-year-old woman with stage IV CLL was admitted for chemotherapy. Her white cell count (WBC) was 364 × 10⁹ cells/L (96% lymphocytes) and 100 × 10⁹ platelets/L. The patient was treated with rituximab, cyclophosphamide, and fludarabine and received bicarbonate and allopurinol. After therapy, the potassium concentration obtained from a lithium-heparin specimen with separator gel was 10.7 mmol/L on a Beckman LX-20 chemistry analyzer (Beckman Coulter). A second lithium-heparin plasma specimen yielded a potassium concentration of 11.2 mmol/L. Results were similar on a different analyzer. Specimens were transported by pneumatic tube, and the time from phlebotomy to analysis was approximately 60 min. No hemolysis was observed. All specimens were obtained using 5-mL Griener Vacuette tubes (GrienerBio-One) unless otherwise noted.