By Donna Kaufman ON May 24, 2010 at 11:47AM

Lady Gaga seems like a woman with few secrets: she's accessible to fans, blunt about sex, honest about her past life as Stephanie Germanotta, and frequently half-naked. But there's one awful secret that she may have been hiding all this time. In an extensive and revealing interview for Sunday's London Times, Gaga admits that she's been tested for lupus -- a genetic disease that killed her favorite aunt. "I have heart palpitations and… things," she tells the interviewer. "But it's okay. It's just from fatigue and other things. I'm very connected to my aunt, Joanne, who died of lupus. It's a very personal thing. I don't want my fans to be worried about me." Gaga doesn't confirm or deny that she has the disease, but she admits that she had trouble breaking at a recent Tokyo concert: "I had a little oxygen, then I went onstage. I was okay. But like I say, I don't want anyone to worry."

Lupus is a manageable, sometimes fatal disease that can cause muscle pains, fevers, anemia, chest pains, sensitivity to light and extreme fatigue (see a full list of symptoms here). The writer hypothesizes that Gaga's recent onstage collapse, her weight loss and the concerts she's cancelled due to fatigue, may actually be flare-ups of lupus -- not an eating disorder, a drug problem or a nervous breakdown, as many have assumed. And Gaga insists that she's more interested in performing than any kind of self-harm: "I certainly don’t have an eating problem. A little MDMA [Ecstasy] once in a while never killed anybody, but I really don’t do drugs. I don’t touch cocaine any more. I don’t smoke. Well, maybe a single cigarette – with whisky – while I’m working, because it just frees my mind a little bit. But I care about my voice. The thrill of my voice being healthy on stage is really special. I take care of myself."

The lupus thing is mostly speculation at this point -- but if Lady Gaga has accomplished her remarkable career while dealing with an incredibly difficult disease, we're even more in awe of her than before.