Hyperleukocytosis and Pseudohyperkalemia in a Patient With Severe SARS-COVID 19 Unmasks Chronic Lymphocytic Leukemia.

Coronavirus disease 2019 (COVID-19) has caused significant morbidity and mortality in a vast majority of the patient population, especially those with malignancies. Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults and is often an indolent disease. High white blood cell counts greater than 120 k/cumm in chronic lymphocytic leukemia may be implicated in cases of COVID-19. Hyperleukocytosis leads to falsely elevated potassium levels due to cell fragility. Pseudohyperkalemia occurs when elevated potassium is present due to potassium movement out of cells during or after a blood sample is drawn. Pseudohyperkalemia may be suspected when elevated potassium is present in asymptomatic patients with no corresponding electrocardiogram findings. The authors present a case of hyperleukocytosis and pseudohyperkalemia in a patient whose COVID-19 infection unmasked CLL.