What would you do for your best friend?
About 3,000 people have kidney transplants each year in the UK and about a third of these are from living donors. Helen Crowther has given one of her kidneys to her best friend Andy Clewes. He has suffered with chronic kidney disease since birth and has recently started to need dialysis treatment.
When Helen first offered Andy her kidney he laughed along, thinking it was a joke.
"But she really meant it and as I got worse she became more insistent until about 12 months ago she said 'right, I definitely want to do it'," he said.
Helen's kidney was removed at the Royal Liverpool Hospital on Tuesday morning.
It was then "whisked down the M62" to Andy in the Manchester Royal Infirmary.
"The last 12 months have gone so slowly and to finally get to this end point is fantastic," the 46-year-old said.
"I was just on the cusp of dialysis, feeling exhausted all the time and unable to concentrate in work - now I can't wait to get my life back. I'm really excited."
Andy, a radio DJ in Macclesfield, said: "I'm incredibly lucky and grateful. It's hard to put into words such a massive thing... it takes a special kind of person to do this."
Born a week apart, the pair struck up their friendship in 2006 after meeting at a charity fundraising event. Last year Helen, 46, was Andy's "best woman" at his wedding.
Helen, a charity worker from Runcorn, said she thought donating a kidney was "the obvious thing to do".
"I do appreciate it's a huge thing. I just didn't want to see Andy poorly. I was aware you can live well with one kidney so couldn't see why you wouldn't do it."
When Andy's mum met Helen for the first time at his wedding and thanked her, she "was in tears".
"It's a bit embarrassing when people are saying you're so brave," she said. "His family were so lovely at the wedding and I was overwhelmed really. I was just doing it as Andy needed to get well. I had the ability to help him.
"It feels like a privilege. I am just so grateful I can do it."
For Andy, he is planning on getting back to a normal life.
"I've been restricted physically up to now but the doctors say I'll get a burst of energy.
"I'm going to want to go off on holiday... to do everything. I think I'm going to be quite annoying."
He said it had made him very aware that others "aren't so fortunate and rely on the kindness of strangers" so he hopes his experience will encourage people to become organ donors as they "really will be changing lives".
Kidneys filter waste products from the blood and convert them to urine.
These waste products can build up in people whose kidneys fail, which is potentially life-threatening and the reason a transplant is needed.
Kidneys are the most common organ donated by a living person and a healthy person can lead a normal life with one working kidney.
Before 2006, living kidney donation was limited to exchanges between family members and friends but since the UK allowed "non-directed altruistic donation" by strangers, more than 500 people have gone ahead with the operation.
There were 1,035 living kidney donor transplants performed in the UK in 2015/2016 - but as of September 2016, there are 5,338 people waiting for a kidney.
You can find more information on the NHS Organ Donation website.
"Nobody wants to see anyone they love on dialysis," said Helen. "This should improve his quality of life. He'll be healthier and that's all I want."
"It's just a couple of months out of my life when I'll feel a bit tired and sore, but for Andy it will be a whole new life."
Andy said: "It's a totally selfless act and she's got a friend for life whether she wants it or not."