MILAN, Italy (AP) — Roberto Alagna, the tenor who quit the stage at Milan’s La Scala after being booed, said he plans to sue the famed opera house for damaging his reputation by dismissing him from the cast of Aida. He claimed he suffered low blood sugar and couldn’t continue the performance.Alagna became the first singer in memory to leave La Scala’s stage during a performance. Video footage shows him giving the audience a fisted salute and walking off Sunday night amid a chorus of boos following the opening aria, Celeste Aida.

He was immediately replaced by a stunned understudy, Antonello Palombi, who wore jeans for the first two acts.

“I was fine when I started, but this problem with my metabolism, if I am very emotional or stressed, my system consumes sugars very quickly,” Alagna said by telephone from the airport in Milan on Friday.

“After that happened to me, the sugars went down dramatically. I couldn’t stay on my feet, I had to sit. I didn’t have the strength.”

Lawyer Marco Rocchini said they would sue La Scala for harming Alagna’s reputation and said he has a certificate from Alagna’s physician confirming low blood sugar levels Sunday night.

“He is accused of abandoning the stage in a fit. The damage to his image is enormous,” Rocchini said, noting that the story had travelled around the world.

La Scala doesn’t plan to sue Alagna for any damage to the “Aida” production, Cella said, but noted it was uncertain whether plans to release a DVD of the production would have to be shelved because of his absence.