Pseudohyponatremia in acute hyperlipemic pancreatitis. A potential pitfall in therapy

Six patients had apparent hyponatremia associated with hyperlipidemia and acute pancreatitis. To our knowledge, only one such patient with acute pancreatitis has previously been described, although the association of hyperlipidemia with "pseudohyponatremia" had been well documented. One of the above patients, whose condition was hemodynamically unstable on admission, developed dangerous symptoms of hyperosmolarity and cerebral dysfunction following aggressive resuscitation with hypertonic saline solution. The pseudohyponatremia results from displacement of water in the serum by the lipids, with sodium existing only in the aqueous phase. This volume displacement results in errors of sodium measurement when the latter is determined by flame photometry or indirect potentiometry, but not when determined by ultracentrifugation and direct potentiometry.