Pseudohyponatremia: A Potentially Dangerous Laboratory Artifact

Pseudohyponatremia is a rare laboratory artifact that inaccurately reports a falsely low serum sodium in the presence of excess lipids and/or proteins. Pseudohyponatremia secondary to excess lipids such as lipoprotein X is less common than hypertriglyceridemia or paraproteinemia and occurs in the setting of cholestasis. Here, we present a case of pseudohyponatremia due to suspected elevated serum lipoprotein X levels. Direct ion measurement of serum sodium levels confirmed normal serum sodium levels and the diagnosis of pseudohyponatremia in the presence of vastly elevated cholesterol levels. Prompt recognition of this clinical entity avoided unnecessary and potentially harmful interventions to "correct" the serum sodium levels.