Piven, who has already missed a few performances of the revival, informed the show's producers that his ill health is due to a high mercury count.
Playwright Mamet told Daily Variety, "I talked to Jeremy on the phone and he told me that he discovered that he had a very high level of mercury. So my understanding is that he is leaving show business to pursue a career as a thermometer."
The show, however, will continue, the playwright said. "The good news is that some really great actors will be helping out and stepping in, which to me is a sign of great heroism and friendship." The New York Post reports that Piven has "been temporarily replaced by" Tony Award winner Norbert Leo Butz (Dirty Rotten Scoundrels).
A spokeswoman for Piven told Variety that although he wanted to continue in the production, his doctors advised him against doing so.
Elisabeth Moss and Raul Esparza will continue in their roles. The production is currently playing a limited engagement through Feb. 22, 2009, at the Ethel Barrymore Theatre.
"Speed-the-Plow focuses on two high-powered Hollywood executives, Charlie Fox and Bobby Gould, who have come up from the mailroom together," according to press notes. "Charlie brings Bobbie a surefire hit with a major star attached. Bobby seems certain to give the green light, until his beautiful new secretary gets involved."
Producers are Jeffrey Richards, Jerry Frankel, Steve Traxler, JK Productions, Ronald Frankel, Ostar Productions, Peggy Hill, Bat-Barry Productions, Ken Davenport, Scott Delman, Ergo Entertainment, Dede Harris, Alan D. Marks, Patty Ann McKinnon, Nicholas Quinn Rosenkranz, Adam Sansiveri, Jamie deRoy and Carl Moellenberg.