Jeremy Piven drops play for mystery ailment

Piven skipped out on his Tuesday and Wednesday shows, then announced he would not be returning for the rest of the run -- he claims his doctor told him his mercury levels are dangerously high and he needs to stop performing immediately.

How'd he get it?

Piven does love sushi and Chinese herbs.

David Mamet responded with characteristic mockery.

"I talked to Jeremy on the phone and he told me that he discovered that he had a very high level of mercury," Mamet says.

"So my understanding is that he is leaving show business to pursue a career as a thermometer."

But Piven's doc says he's not making it up. In fact, mercury poisoning is a serious ailment that can take years to cure.

"He's disappointed that I had to pull the plug. But I think he's hurt more by the comments that he's not trying or that he walked away. He's been working straight for 30 years. He doesn't walk away; I tore him away from it," says Dr. Carlon Colker.