Blanco left to be with his mother, who has fallen ill, and will be gone for an undisclosed amount of time, though he can only remain on the bereavement list for three to seven days.
"He felt it necessary that he be there, so [per] organization policy, we give him that freedom to take care of that situation," manager Jerry Manuel said.
Thole is with the Mets for the first time this season after hitting .321 in 53 at-bats with the team in 2009.
The 23-year old catcher has struggled in Triple-A this season, hitting .203 with a .599 OPS in 89 plate appearances.
"[It's the] first time I've struggled in my whole career," Thole said. "I got off to a slow start, but I'm slowly digging my way out now."
Manuel has never been worried about Thole's hitting and was glad to see that the young catcher has improved his defense since Spring Training. He said that Thole could get the start on Wednesday afternoon depending on how Rod Barajas feels after catching Tuesday night's game. -- Kyle Maistri