In a telephone interview on Thursday, Dr. Colker said that Mr. Piven had come to him soon after the show had opened, complaining of excessive fatigue and exhaustion. Noting Mr. Piven’s artistic lineage — his parents founded the Piven Theater Workshop near Chicago — Dr. Colker said, “For him, he’s used to the rigors of an acting career, so he knows the ropes.”  Dr. Colker said that an initial battery of tests on Mr. Piven had shown normal results. But after Mr. Piven said he was a frequent sushi eater who consumed fish about twice a day, and that he used herbal remedies, Dr. Colker tested him for heavy metals.  Dr. Colker said that these tests revealed “a very, very elevated level of mercury” in Mr. Piven’s blood, adding that it was five to six times the upper limit that is typically measured. Left untreated, Dr. Colker said, the condition could result in heart problems, cognitive problems, renal failure and, in very extreme cases, death. He said that he told Mr. Piven he could continue in the show, but only with extreme caution.  “In his case,” Dr. Colker said, “the pure exhaustion could affect his ability to perform. But it was his dream to perform on Broadway, and let’s face it, the show wasn’t a flop.”  Dr. Colker said that the producers of “Speed-the-Plow” were informed of Mr. Piven’s condition last week, but that the actor kept pushing himself to perform. Then this week, the doctor said, Mr. Piven was hospitalized when his exhaustion worsened. He declined to say at what hospital Mr. Piven was treated.  Dr. Colker said he circulated a letter to the show’s producers, after Mr. Piven’s hospitalization, recommending that he withdraw. Dr. Colker stressed that it was not Mr. Piven’s decision. “It’s important to underscore that,” he said. “It was my decision.”  Mr. Piven had asked earlier this month to be released from the show a week or two ahead of its Feb. 22 closing date, saying that he was exhausted, Jeffrey Richards, a producer of “Speed-the-Plow,” said. Later, Mr. Richards said, the show’s schedule was modified so that Mr. Piven would be able to attend the Golden Globe Awards in Los Angeles on Jan. 11.  After making this accommodation, Mr. Richards said, he was informed by Mr. Piven’s representatives that the actor would not return to the show after the Golden Globes. Mr. Piven, he said, had spoken to other actors and managers in an effort to find his own replacement.  “It was rather unusual,” Mr. Richards said. “He was trying to be quote-unquote helpful.”  Dr. Roberta F. White, the chairwoman of the department of environmental health at Boston University, said that the consumption of fish high in quantities of methylmercury could cause health problems consistent with Mr. Piven’s symptoms. “The higher the fish is on the food chain, the more methylmercury there is likely to be,” Dr. White said in a telephone interview.  Those fish, she said, included swordfish, sea bass and certain types of tuna. But Dr. Peter Rabinowitz, the director of clinical services at the Yale Occupational and Environmental Medicine program, who treats metal toxicity among other work-related hazards, said that most adult patients at his clinic who are found to have high levels of mercury “are doing well, without adverse health effects.”  Having learned on Monday that Mr. Piven was leaving the show immediately, Mr. Richards and his producing team contacted Mr. Butz, a Tony Award winner for “Dirty Rotten Scoundrels,” and Mr. Macy, who has frequently worked with Mr. Mamet in plays and films. Mr. Richards said both new recruits agreed to join the show on 24 hours’ notice, and are already learning the play.  “We were proud to present Jeremy in his Broadway debut,” Mr. Richards said, “and we’re sorry to see it end this way.”  At least one person associated with the play seemed less forgiving about Mr. Piven’s departure. Speaking to Daily Variety, Mr. Mamet said, “My understanding is that he is leaving show business to pursue a career as a thermometer.”  A version of this article appears in print on , on Page C1 of the New York edition with the headline: Piven Leaves Show Amid Health Concerns. Order Reprints| Today's Paper|Subscribe
A real-life fish story has resulted in Jeremy Piven’s withdrawal from the current Broadway revival of the David Mamet comedy “Speed-the-Plow.”