Kearns was originally in the lineup against Philadelphia, but after arriving at the ballpark he complained he didn't feel well and went to a hospital for evaluation. Further tests were planned, manager Mike Redmond said after the game.
"He's resting well," Redmond said. "It looks like everything is fine for now. We'll probably know more Monday."
Justin Ruggiano replaced Kearns in the lineup, and the Marlins lost 2-1.
Kearns is 0 for 10 this season, his 12th in the major leagues.