Abstract: PUB087
Reverse Pseudohyperkalemia in Chronic Lymphocytic Leukemia, a Diagnostic Pitfall
Session Information
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Author
- Aslam, Ishaq, Sutter Roseville Medical Center, Roseville, California, United States
Introduction
Reverse pseudohyperkalemia is a laboratory artifact characterized by falsely elevated plasma potassium with normal serum potassium, typically seen in extreme leukocytosis. This phenomenon occurs when heparinized plasma tubes and centrifugation cause in vitro leakage of potassium from fragile leukemic lymphocytes, falsely elevating measured levels. Clinicians must remain vigilant when evaluating hyperkalemia in patients with hematologic malignancies.
Case Description
A 67-year-old woman with chronic lymphocytic leukemia presented after routine labs revealed a WBC of 416 ×10^9/L and plasma potassium of 6.7 mmol/L. Despite markedly elevated potassium, she was asymptomatic with a normal ECG. She was admitted to the ICU and treated with insulin/dextrose, calcium gluconate, albuterol, and sodium zirconium cyclosilicate. Plasma potassium remained persistently elevated despite aggressive therapy, prompting nephrology consultation for emergent hemodialysis. Recognizing the discordance between labs and clinical status, arterial blood gas (ABG) testing was obtained and demonstrated normokalemia. Repeat testing using non-heparinized serum confirmed normal potassium, establishing the diagnosis of reverse pseudohyperkalemia. Unnecessary interventions were halted and the patient was eventually discharged home.
Discussion
This case highlights reverse pseudohyperkalemia as a clinically significant diagnostic pitfall. CLL patients harbor fragile lymphocytes with increased membrane permeability; heparin exposure, mechanical stress, and centrifugation promote potassium leakage into plasma, falsely elevating measured levels. Failure to recognize this artifact can lead to iatrogenic hypokalemia, hypoglycemia, unnecessary ICU admission, or dialysis. ABG potassium measurement provides rapid, reliable confirmation of true serum levels. Severe hyperkalemia without ECG changes in a patient with extreme leukocytosis should prompt consideration of reverse pseudohyperkalemia and confirmatory testing with ABG or non-heparinized serum before initiating treatment
Comparing serial potassium levels