"He's had some symptoms, so the concern is that maybe it's concussion-related," general manager Sandy Alderson said. "We'll run the tests and see where he's at."
d'Arnaud began feeling dizziness after Tuesday's game, prompting the Mets to proceed with their standard head-injury protocol. Though Collins said the team was being "pretty cautious" and that backup Anthony Recker was scheduled to start behind the plate Wednesday anyway, the Mets were concerned enough to call up Triple-A Las Vegas catcher Juan Centeno on the taxi squad.
If the Mets decide to place d'Arnaud on the seven-day head-injury disabled list Thursday, they will activate Centeno as a backup. If not, they will simply recall reliever Josh Edgin from Las Vegas. The Mets have one open roster spot after outrighting relief pitcher Kyle Farnsworth late Wednesday night.
d'Arnaud is batting .196 with three home runs, appearing in 31 of the Mets' first 39 games.
Anthony DiComo is a reporter for MLB.com. Follow him on Twitter @AnthonyDicomo. This story was not subject to the approval of Major League Baseball or its clubs.