Hyperkalemia in the setting of severe leukocytosis: Should you treat?

Severe hyperkalemia is a common and life-threatening problem presenting to the emergency department. Rapid correction of the electrolyte abnormality is essential but doing so can be detrimental in circumstances under which delaying treatment for confirmation is required. Our case exemplifies one of those scenarios: pseudohyperkalemia in the setting of severe leukocytosis. An elderly woman with long-standing but untreated chronic lymphocytic leukemia presented with a left hip fracture. She was found to have a potassium level of 8.4 mEq/L without symptoms of hyperkalemia, renal disease, or EKG findings. Her white blood cell count was 444 K/uL. Despite a potentially life-threatening hyperkalemia, correction was deferred pending confirmation by venous whole blood, which revealed a normal potassium level. Pseudohyperkalemia can occur in the setting of severe leukocytosis. It is important for emergency physicians to recognize this phenomenon and avoid iatrogenic hypokalemia. The pathophysiology behind this phenomenon and the methods for correct analysis are presented here.