One Direction's Liam Payne has revealed that a medical problem he was born with has finally "fixed" itself.

The heartthrob opened up about the fact that he only had one fully functioning kidney in the band's official book, 'Dare To Dream', and explained that he was born with the ailment:

"I've only got one kidney because when I was born I was effectively dead. I was born three weeks early and I kept being ill. From the age of zero to four I was always in hospital having tests done but they couldn't find out what was wrong."

"They discovered that one of my kidneys wasn't working properly and it had scarred. I had to have 32 injections in my arm in the morning and evening to try and make me better. I've still got both kidneys but one doesn't work so I have to be careful not to drink too much, even water, and I have to keep myself as healthy as possible."

Earlier this evening (August 7), Payne took to social networking site Twitter and told his 5.1 million followers that an ultrasound scan carried out today has shown that the defunct kidney is now working:

"Just been for an ultrasound on my kidney turns out its fixed form [sic] when I was a baby!!! :o so now I have two :) #weirdnewsoftheday"