Pseudohyponatremia Secondary to Hypercholesterolemia in the Setting of Intrahepatic Cholestasis due to Metastatic Liver Disease: A Case Report and Review of the Literature

OBJECTIVE. We describe a rare case of pseudohyponatremia in the setting of hypercholesterolemia caused by cholestasis due to metastatic liver disease and provide a review of the published cases in the literature. CASE REPORT. We report a case of pseudohyponatremia in a 60-year-old man with rectal cancer with extensive metastasis to the liver. While assessing the patient for hyponatremia, extremely elevated serum cholesterol with normal serum osmolality was detected leading to the diagnosis of pseudohyponatremia. This is one of very few reports of pseudohyponatremia in patients with elevated cholesterol in cholestatic liver disease. CONCLUSION. Hypercholesterolemia is an exceedingly rare cause for pseudohyponatremia. Although pseudohyponatremia per se does not carry a risk to the patient, the delay in diagnosis and treatment plans may pose additional risks. Pseudohyponatremia needs to be considered in patients with low sodium and co-existing cholestasis from metastatic liver disease.