Case Presentation: A 56-year-old man with history of hypertension on amlodipine, hydralazine, losartan, spironolactone, and torsemide, uncontrolled insulin dependent type 2 diabetes mellitus, chronic kidney disease (CKD) stage IIIb, and chronic lymphocytic leukemia (CLL) with extreme leukocytosis of 268,600/uL on admission presented to the hospital for progressive shortness of breath and was found to be in mild acute diastolic heart failure. On admission, patient’s potassium was 5.6 meq/L and creatinine was at baseline 1.67 mg/dL, thus losartan and spironolactone were held. Patient also received furosemide 40 mg intravenously for diuresis. The next day, the patient’s potassium was further elevated at 6.3 meq/L. Creatinine was 1.68 mg/dL and EKG was negative for conduction abnormalities. Patient received albuterol 2.5mL, kayexalate 30 mg, insulin regular 6 units with subsequent potassium levels trending down to 4.5 meq/L. Patient was seen by nephrology. Hyperkalemia was felt to be related to combination of hyporeninemic hypoaldosteronism from diabetes, CKD, losartan and spironolactone usage and excess potassium intake in diet (patient was using salt substitutes). Four days later, despite discontinuation of possible culprit medicines and continued diuresis, patient was again noted to have an elevated potassium of 5.2 meq/L. In the setting of extreme leukocytosis, suspicion for pseudohyperkalemia arose. Thus repeat serum potassium was obtained via an arterial blood gas machine which revealed a potassium of 3.5 meq/L.
Discussion: Pseudohyperkalemia is a rise in measured serum potassium concentration without change in effective plasma potassium concentration. In chronic lymphocytic leukemia with extreme leukocytosis, measured levels of potassium are potentially elevated due to lysis of increasingly fragile leukemic white cells during or after collection resulting in release of intracellular potassium. Failure to diagnose can lead to unnecessary hospitalization and multiple superfluous interventions that may lead to dangerous hypokalemia. Avoiding pneumatic tube collection and comparing serum to plasma potassium can help clinicians effectively differentiate and avoid excessive treatment.
Conclusions: Clinicians should evaluate for pseudohyperkalemia in patients with elevated potassium and extreme leukocytosis of chronic lymphocytic leukemia.