The team is awaiting results on the blood work of Pagan, who left Sunday's game in the fifth inning due to dizziness. Jason Pridie started in center field Monday evening in Pagan's place.
"For about a week now, in the middle of the game, he just starts to lose energy," Mets manager Terry Collins said. "We'll just give him a little checkup."
Pagan, who said Sunday that he does not consider the issue serious, is batting .232 with four home runs and 18 stolen bases in 71 games. He has drawn mild rumors as a possible trade target for contenders prior to Sunday's non-waiver deadline.