Following his mid-game removal on Friday night, Martin complained of pain in the hip area.
"Everyone wanted to talk about the hamstring," Hurdle said, "but in the [dugout] tunnel, he kept talking about his hip. Could the hamstring have led to the hip? Whatever … that's why he's going back for further testing, to try to actually pinpoint whether the hamstring is causing the connection to the hip pain."
Concern first arose about the veteran catcher when he slid across the plate to score the winning run in the Pirates' walk-off win over the Reds on Monday, was slow to rise, then spent several minutes sitting disconsolately in the dugout. Martin sat out games Wednesday and Thursday, but was back in the lineup for Friday night's game here.
After being visibly impaired, he was removed following his at-bat in the top of the sixth. Tony Sanchez was recalled from Triple-A Indianapolis and moves in as the primary catcher, with Chris Stewart now serving as his backup.
"It's about the welfare of the player," said Hurdle, who had obviously been facing a daily dilemma about Martin's availability. "To give him and the training staff every opportunity to work through what he needs to get back on the field productively.
"We all realized last night a couple days [of rest] were not enough. The next step was to just shut him down … so the closure from that is good for everybody. Now we can focus on his rehab. He knows this is his best opportunity to get well."
This marks only the second time the nine-year veteran has gone on the disabled list. He missed the final two months of the 2010 season with a torn labrum in his right hip.
Tom Singer is a reporter for MLB.com and writes an MLBlog Change for a Nickel. He can also be found on Twitter @Tom_Singer. Cash Kruth is a reporter for MLB.com. Follow him on Twitter at @cashkruth. This story was not subject to the approval of Major League Baseball or its clubs.