The Cubs fear Caratini suffered a hamate fracture. He'll have a CT scan Friday to figure out the extent of the injury.
"We don't expect it to be short," manager Joe Maddon said of how long Caratini could be out.
Caratini was informed by trainers that if he does have a hamate fracture, he'll be out at least three or four weeks.
Caratini believes he injured himself on a swing early in his at-bat in the seventh inning. Despite the discomfort, he finished his at-bat and hit an RBI double that gave Chicago a 2-0 lead. Caratini then didn't return defensively for the top of the eighth inning, with Willson Contreras replacing him.
Caratini was off to a hot starting, hitting .588 (10-of-17) with one homer and six RBIs. He was 2-of-3 with two doubles Thursday.
The Cubs are expected to call up catcher Taylor Davis from Triple-A Iowa to take Caratini's place.