Pseudohyponatraemia secondary to hyperlipidaemia in obstructive jaundice

A 44-year-old man with uncontrolled diabetes and chronic pancreatitis presented with abdominal pain, jaundice and unintentional weight loss. Laboratory investigations were significant for hyponatraemia, an obstructive pattern of liver enzymes. Imaging was consistent with intrahepatic and extrahepatic biliary obstruction, and endoscopic evaluation revealed a long common bile duct stricture. Intravascular volume depletion, beer potomania and syndrome of inappropriate antidiuretic hormone (with concern for biliary or pancreatic malignancy) were considered in the work-up for the aetiology of the hyponatraemia. After 4 days of conventional treatment, hyponatraemia persisted. Lipid panel obtained revealed very high levels of total cholesterol. The patient underwent a successful biliary diversion and reconstruction surgery. Follow-up after 3 months showed a clinically stable patient with resolution of elevated liver enzymes, hyperlipidaemia and hyponatraemia. We illustrate this rare case of hyponatraemia secondary to hyperlipidaemia in obstructive biliary cholestasis. It is important for physicians to thoroughly investigate the aetiology of hyponatraemia at its onset.