Pseudohyponatremia Caused by Severe Hemolysis

A 78-year-old man with influenza presented to the hospital. Initial blood tests revealed severe hemolysis accompanied by a decreased serum sodium concentration. However, repeat testing showed no hemolysis, and the serum sodium level was within the normal range. Notably, the serum sodium concentration in the initial sample, when measured using a blood gas analyzer, was also normal. These findings led to a diagnosis of pseudohyponatremia secondary to severe hemolysis. The underlying mechanisms of this condition are discussed herein.