Arianna Moore's kidney failed when she was just seven weeks old and ever since the toddler from Minnesota, US, has had to spend every single day hooked up to a dialysis machine for 10 hours at a time.
Now Arianna's ordeal is ending thanks to the kindness of Christy Harding, a 37-year-old mum who lives in Florida - 1,500 miles away from Arianna.
The pair have never met, but Christy felt moved to volunteer to donate her kidney after reading a Facebook post about Arianna's plight.
Soon after she was born, Arianna was diagnosed with a rare genetic condition called Diffuse Mesangial Sclerosis, which causes scarring on her kidneys.
Two years of dialysis treatment has left her 10 pounds lighter and four inches shorter than her twin sister Nevaeh.
Desperate to find her daughter a kidney donor, Arianna's mother, Ashley Booth set up the ALL4MOORE Facebook page in the hope of raising awareness about the toddler's condition.
"I had no faith that we'd find a kidney donor on Facebook but I sure as heck was going to try," Ashley told GoodMorningAmerica.com.
The social media appeal turned out to be more successful than Ashley could ever have hoped.
"One of my friends shared one of Arianna's pictures and it showed up on my timeline," said Christy. "For some reason, I stopped and started thinking about it, and I just knew I had to make a phone call."
Christy has a two-year-old daughter herself and she says she was inspired to donate her kidney because she hoped someone would do the same for her daughter if the need arose.
She contacted the living donor center at Arianna's children's hospital to make sure her type-O blood would be a match and discovered she was a perfect donor.
Christy emailed Ashley to let her know that she would donate her kidney, and on April 23, Ashley updated Arianna's Facebook page with the following message:
"Tonight a wonderful lady emailed me... I haven't met her yet but I can't wait to meet her and thank her in person for this selfless gift she's giving my baby girl.
"There are no words to explain the overwhelming emotions I feel. I got goosebumps for the second time today reading her email. I'll never be able to thank her and her family because there is no way to thank someone for saving your daughters life."
Both Christy and Arianna are scheduled to undergo surgery in Minneapolis on May 7.
"It's so amazing. We haven't even met her yet," said Ashley. "I cannot wait for next Monday. I don't know if I'll be able to let of go of her once I hug her."
But that's not the only selfless act Christy has done for Arianna and her family. She has also set up a Go Fund Me to raise money to send them all to Disney World in Florida.
"My family and I are big Disney fans," Christy explained. "We are blessed enough to have season passes and take trips down there often. I know living in Minnesota, it's not the same for them. I made the assumption this isn't something they'd be able to do, but every child should have the chance."
What an amazing woman!
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