Turner went through an examination with team doctors, Rand said.
"The other day in his outing, he had trouble getting loose and trouble finishing off his pitches," Rand said. "So we're basically shutting him down at this point in time to deal with a little bit of a tendinitis issue in his shoulder. We're working on treatment, range of motion and strength until we feel comfortable putting him back out there."
At the very least, that will cost Turner his next turn in the rotation, including the next edition of the fifth-starter competition Saturday against the Cardinals at Joker Marchant Stadium. Whether he could be cleared to resume throwing and be ready again for the next rotation turn after that is questionable.
Manager Jim Leyland downplayed the concern over the setback Wednesday.
"For me, this is just a burp," Leyland said.
When asked if this knocks Turner out of the fifth-starter contest, Leyland said it did not. But he acknowledged it puts him behind.
"I would say it lessens his chances of being the fifth starter," Leyland said. "Does it take him out? No."
Turner, the Tigers' top prospect who was rated No. 15 on MLB.com's Top 100 Prospects list, struggled through his last outing on Monday, giving up a six-run inning to the Mets, fueled by a Lucas Duda grand slam. Five of those runs were earned, thanks to Turner's throwing error trying to start a double play.
Rand said Turner won't pick up a baseball for a week.
"He was started on medication, and we're going to let that run for a week," Rand said.
Turner said that Monday was the first time he had trouble "to that degree" getting his arm loose and extending his arm on his pitches. It had happened before, he acknowledged, but not nearly that bad.
"Being able to throw in the bullpen is great, but if you can't get loose, that's really the biggest thing," Turner said. "And I just didn't feel like I could."
That carried into the game.
"I think anybody who was watching him felt that he wasn't himself out there," Rand said.
After that, Turner went through diagnostic tests. At this point, it doesn't sound like anything more is scheduled.
"All our diagnostics we needed to do, have been done," Rand said.
Leyland said after that outing that Turner looked like he had "dead arm," a term that was far more common in past years. Back then, it was the term for a period of Spring Training when pitchers were getting their arm in shape for game readiness. Now, with as much time as pitchers throw before they arrive at camp, it's a rare term.
"Dead arm to me is just when you can't put a finger on it," Rand said. "You can't say you're sore in this [area], you really can't pinpoint it, whether your arm's tired or you just don't feel like it has any life. You feel like you just don't have that pop [in your pitches]. And guys go through that in various stages.
"You don't really hear as much of it anymore. Maybe we do a better job in assessing it, that type of thing. But players still go through it."
In other injury news, infielder Danny Worth remains day-to-day with soreness in his mid to lower back on his right side. He said Wednesday morning he felt a lot better and was hoping to take batting practice and infield work, but probably wouldn't play in Wednesday's game against the Mets.