"He's resting well," Marlins manager Mike Redmond said. "But they're going to keep him overnight. I think they're still doing some tests on him. It looks like everything is fine for now. We'll probably know more tomorrow."
Initially, Kearns was in the Marlins starting lineup for Sunday's series finale, which was won 2-1 by the Phillies.
Shortly after arriving at the ballpark, Kearns did not feel right. He was checked out by the Marlins' trainers, who quickly sent him to the hospital.
In his second season with Miami, Kearns is popular with his teammates.
Reliever Jon Rauch was also a teammate of Kearns a few years ago in Washington.
"Obviously, he's a leader in the clubhouse," Rauch said. "You guys saw what he was able to do last year, and having a veteran around like that. Plus, he's just a standup guy and a good teammate. I played with him in D.C., and I've known him a long time. I played against him in college. You never want to see anything like that happen. You wish him the best for a speedy recovery."
Just two weeks into the season, the Marlins are dealing with plenty of adversity.
The loss on Sunday dropped their record to 2-10, and the team is having a tough time keeping players healthy.
"Immediately, when he left, we started trying to figure out when we could go see him," said Kevin Slowey, Miami's starting pitcher Sunday. "Austin is the kind of guy, he's a great player, but he's a much better friend. I think everybody in this clubhouse feels that way about Austin. He's a good man.
"Normally, he's one of the first guys to greet you. He greets everybody, and he's always aware of what's going on in your life. To guys in this clubhouse, in this moment, our season may not be how we want it to be, as we look at it right now. I think we have some bigger things to worry about."
Miami's outfield Sunday was without Kearns and All-Star Giancarlo Stanton, who missed his third straight game with a bruised left shoulder.
Justin Ruggiano was scratched from the lineup Saturday because of a tight right groin. The plan was to give Ruggiano Sunday off, but he was called upon to start in right field in place of Kearns.
Kearns started in right field in Saturday's 2-1 win.
Injuries have been piling up since the end of Spring Training. The day before the season started, starting pitchers Nathan Eovaldi and Henderson Alvarez were placed on the 15-day disabled list with right shoulder inflammation. And two games into the season, first baseman Casey Kotchman strained his left hamstring and was placed on the DL.
"Obviously, we've had a lot of stuff starting from the last week of Spring Training, losing two starters," Redmond said. "And losing your first baseman. Stanton is out. Kearns is out. Ruggiano has a tight groin. My first two weeks of managing in the Major Leagues has definitely been an adventure."