Pseudohyponatremia Leading to a Fatal Outcome in a Patient With Familial Hypertriglyceridemia

Serum sodium assay is a commonly performed laboratory test in a clinical setting and the results are taken for granted without being aware of the actual methods involved. In conditions like hyperlipidemia and hyperproteinemia, excessive lipids in serum dilute the water component of the serum. Since sodium is dissolved only in the aqueous phase of serum, the sodium content per unit volume of plasma is reduced. Currently, most of the laboratories use the indirect ion-selective electrode method (ISE), where the plasma sample is diluted before the measurement. Indirect ISE may not give accurate results in conditions with higher serum lipid and protein levels. Overcorrection of the serum sodium levels in pseudohyponatremia may cause serious complications. We report a case of a 26-year-old Asian male with a past medical history of chronic pancreatitis, familial hypertriglyceridemia, and fatty liver who presented to the emergency department with acute pancreatitis. Initially, the patient was found to have hyponatremia and he was started on hypertonic saline for one day. Later the patient's condition deteriorated and then it was determined that serum sodium results were a measurement artifact since the patient had extremely high levels of triglycerides. After realizing that it was a measurement artifact, the saline infusion was stopped and he was started on desmopressin. However, the patient deteriorated neurologically and expired later. As this patient had normal sodium levels, administration of hypertonic saline led to a fatal outcome.