Boss Paul Jewell had been hoping to loan out the Brazilian centre back so he could get match practice under his belt.
However an injury to captain Arjan De Zeeuw in training means that the Latics boss is now reluctant to let Thome leave. At least until he knows how serious De Zeeuw's injury is.
The Rams are desperate to get a defender in as they hope to push for the play-offs after the departure of Tom Huddlestone to Tottenham in the summer.
Derby boss Brown said: "I was in contact with Paul Jewell and he sounded quite enthusiastic about it all but now it sounds like Arjan De Zeeuw has limped out of training and Paul's suddenly got defensive problems of his own. So we're left desperately trying to get a new body in."