Differentiating Pseudohyperkalemia From True Hyperkalemia in a Patient With Chronic Lymphocytic Leukemia and Diverticulitis

Acute changes in electrolyte levels can result in severe physiologic complications. Rapid treatment of abnormally elevated potassium levels is essential due to the increased risk of potentially fatal cardiac arrhythmias. However, there are a number of circumstances that can lead to falsely elevated serum potassium levels, including fist clenching during phlebotomy and hemolysis of hematocytes during laboratory processing. Here we present a case of an elderly woman with chronic lymphocytic leukemia who presented with lower left quadrant pain and hematochezia. Laboratory tests revealed an elevated serum potassium level (7.5 mmol/L) on initial testing, in the absence of hyperkalemia symptoms, EKG changes, and hemolysis of the blood specimen. Abdominal CT revealed inflammatory changes consistent with diverticulitis. She was treated with intravenous calcium, insulin, glucose, and bicarbonate for her hyperkalemia and admitted for treatment for diverticulitis. A subsequent serum potassium level (3.9 mmol/L) and discussion with the hospitalist suggested a diagnosis of leukolysis-induced pseudohyperkalemia, and further treatment of hyperkalemia was halted. This case serves to remind current and future physicians about the importance of maintaining clinical suspicion and clarifying unexpected laboratory readings when the clinical picture and results do not completely align.

Keywords: chronic lymphocytic leukemia; diverticulitis; elevated potassium; hyperkalemia; pseudohyperkalemia.