UFC heavyweight champion
Lesnar, who twice pushed a fight back recently due to a bout with mononucleosis, is facing a far more significant illness that is potentially career-threatening.
"There's a possibility Lesnar will never fight again," White told TMZ.
White plans to have Lesnar transferred to the Mayo Clinic in Rochester, Minn. for further diagnosis and treatment.
During the UFC 105 post-fight press conference, White declined to specify Lesnar's illness to respect the star's privacy, but did state that Lesnar neither has cancer nor AIDS.
Lesnar was scheduled to defend his belt against
"I can't really talk about it right now, but he is in rough shape. He's in really bad shape," White said Saturday. "I'm actually probably going to fly to go see him, and we're going to probably have to do some stuff to take care of this guy. He is not well, and he's not getting any better."