Loewen, who was making just his third appearance since coming off the disabled list on June 30, left the game with discomfort in his left elbow -- the same elbow he just spent nine weeks rehabbing after enduring surgery and rehab in 2007 to repair a stress fracture in the joint.
Manager Dave Trembley said after the game that Loewen would get a CT scan Monday morning but that he did not expect the reliever to be back out on the mound any time soon.
"He felt a sharp pain in his elbow," Trembley said. "The pitch before, I saw him shake his hand and I jumped up, Richie jumped up, [pitching coach Rick Kranitz] was there, and [Loewen] really didn't know what it was. That second pitch he said he really felt a much sharper type of pain."
Loewen, who declined comment, threw 27 pitches in relief of Orioles starter Radhames Liz, allowing two walks and striking out one batter in his one full inning of work. He left the game with two outs in the fifth and a 2-2 count on Rangers third baseman German Duran.
Loewen went to the disabled list initially on April 24 with soreness in that surgically repaired left elbow. He then came back to the Orioles after nine rehab appearances insisting that the elbow pain was no longer an issue and he was fully ready to return to the team.
"I personally made a phone call to him the day before he got back up here because in my mind I wanted to make sure he was 100 percent physically and mentally and that he'd passed every test," Trembley said. "He told me he did and I believed him. He just told me right [now] that he never felt anything the whole time he was rehabbing. I'm not good enough to understand the kind of surgery he had and the screw that he's got in his elbow. Obviously we have to get it right, but I don't think there's any question, I think he was [100 percent], and now we have a definite setback."
The southpaw missed all but six starts in the 2007 season with the injured elbow and began the 2008 season pitching with discomfort -- likely due to the screw inserted into the joint during surgery. He was unable to make it out of the month of April without needing another trip to the DL.
Amanda Comak is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.