New research calls into question what's in those IV bags that nearly every hospitalized patient gets. Using a different intravenous fluid instead of the usual saline greatly reduced the risk of death or kidney damage, two large studies found.

The difference could mean 50,000 to 70,000 fewer deaths and 100,000 fewer cases of kidney failure each year in the U.S., researchers estimate. Some doctors are hoping the results will persuade more hospitals to switch.

"We've been sounding the alarm for 20 years" about possible harms from saline, said Dr. John Kellum, a critical care specialist at the Uni...