The presence of even mild hyponatremia before surgery is associated with increased perioperative mortality, according to a cohort study in the Archives of Internal Medicine.

Nearly 1 million U.S. adult patients in a surgical-quality registry had their sodium levels measured within 90 days before surgery. About 8% of patients had hyponatremia (defined as a serum sodium level under 135 mEq/L), with most of these being only mildly hyponatremic (values ranging from 130 to 134 mEq/L).

The study’s primary outcome, mortality within 30 days after surgery, was higher in those with hyponatremia than in those with normal sodium levels (5.2% vs. 1.3%); the difference remained significant even after adjustment for other risk factors such as smoking and functional health status.

Editorialists comment that the findings are not surprising, given the comorbidities associated with hyponatremia. They say it remains an open question whether elective surgery should be postponed in the face of mild hyponatremia, “but the diagnosis should contribute to the informed consent process.”

Source:Archives of Internal Medicine