The organization announced Saturday that Caldwell, slated to be Miami's assistant head coach and quarterbacks coach, will take a leave of absence to address health issues and instead serve as a team consultant for the 2019 season.
"I will be stepping back due to some medical complications that require my full attention," Caldwell said, via the team's official site. "I want to thank Stephen Ross, Chris Grier, Coach Flores and the rest of the organization for the support they have given me and my family."
Dolphins coach Brian Flores added: "Our focus is on Jim's health and supporting him in every way that we can. With his knowledge and experience, Jim has been an invaluable member to our coaching staff and will continue to serve as a sounding board for me throughout the season."
Assistant QBs coach Jerry Schuplinski has been regarded as ready for a more prominent role and will have that opportunity in Caldwell's absence, NFL Network Insider Ian Rapoport reported.
The 64-year-old Caldwell joined the Dolphins' staff this past February and has 17 years of NFL coaching experience. He compiled a 62-50 record over seven seasons as the head coach of the Indianapolis Colts (2009-11) and Detroit Lions (2014-17), reaching a Super Bowl with the former in his first season. His other 10 seasons in the league were spent as a quarterbacks coach, including two years as an offensive coordinator.