Alliance Party leader Naomi Long has announced she is to undergo surgery for endometriosis.
Writing on social media, Naomi Long revealed that she has suffered from the condition for most of her adult life.
Speaking to the BBC, she said the pain had been so severe at times that she had to be admitted to hospital to deal with it.
Mrs Long expects to be off work for up to 10 weeks to recover.
"I've have really had this condition since adulthood and it's something that has become more and more difficult to manage over time," Mrs Long told BBC NI's Good Morning Ulster programme.
"I've tried a number of different options in terms of management, none of which have been very successful.
"So because of the deterioration, the fact that I have been in chronic pain really for the last couple of years and having to manage that with a lot of pain medication, the decision was taken that I'd be better to have surgery."
Mrs Long said it was not something she had talked about but wanted to let people know what was happening.
"I just wanted to let people know that when I disappeared for a while it wasn't anything sinister, because unfortunately when you're in the public eye, if you're in hospital, people start to make all sorts of speculation as to what it may be," she said.
What is endometriosis?
Endometriosis is the name given to the condition where cells like the ones in the lining of the womb (uterus) are found elsewhere in the body - including the bowel, ovaries or bladder.
The cells act in the same way as during a period, building up and breaking down.
But they have no way of getting out of the body and can cause inflammation, pain and the formation of scar tissue.
"One of the things that has surprised me is that, even in just the short time since I made public that I was going into hospital, the number of women who have come forward with the same condition and like myself actually didn't find out until quite late in life that that's what it was.
"They were being treated for a whole range of other things that it might be, irritable bowel syndrome and a whole series of other things, before they found out what the cause of the problem was, because it's very much an under-diagnosed condition." Mrs Long said she had "every confidence" in deputy leader Stephen Farry to act for her when she was not available in the short-term during talks to restore devolution.
"The sad reality is that I'm missing absolutely nothing at the moment, because there's nothing going on at Stormont and I think that's a real shame," she said.
"People seem to have now disappeared off and are taking the summer to themselves which I think shouldn't be happening. But hopefully by the time the talks start up again I'll be well in to my recovery period".