"It was just a couple of days before Christmas and we were due to go away on a family holiday and Maddie woke with puffy eyes."
Mrs Collins said she and her husband, Adam, thought Maddie was showing an allergy to hay or grass as they'd moved to rural West Melton in Canterbury only six weeks earlier.
But when they went to the doctor to get some antihistamines, Mrs Collins was told to take Maddie straight to hospital.
Luckily, the doctor had seen a similar case before.
"Typically, GPs don't pick it up in girls. Boys, it's a lot easier, because their testicles swell so it's easy to see that there's something wrong. But for girls, quite often it's misdiagnosed as an allergy," said Mrs Collins.
About 95 per cent of children with nephrotic syndrome grow out of the disease by their mid-teens, following high-dose steroid treatment.
But Maddie had no response to the typical steroid treatment, or to a 12-week course of chemotherapy.
"Even though it's not a cancer, they do use some of the cancer drugs to try and get the remission. But for Maddie it didn't work," said Mrs Collins.
"Then we tried immunosuppressants and some other cancer drugs, but we weren't [able] to get any remission."
Maddie's potentially curable nephrotic syndrome has since developed into Focal Segmental Glomerulosclerosis (FSGS) - which is incurable.
With one kidney removed last August, Maddie will have her last kidney taken out in the Starship hospital in Auckland next week.
A kidney transplant is scheduled for October 10, and her dad will be the donor.
"A transplant is just another form of treatment, it is not a cure," said Mrs Collins.
"Maddie is at risk of her disease coming back and it can come back as quickly as 24 hours after a transplant. But what we're hoping for with this transplant is to buy her some time to have some years of a normal childhood."
What Maddie is most looking forward to after her transplant is something other little girls might take for granted. "She can go to sleepovers, which is what she's really excited about."
The couple will stay in Ronald McDonald House in Auckland for three months after Maddie's operation.
While their accommodation is free, they have to pay for their groceries and living expenses.
This is on top of their regular expenses back home, where their other children Georgia, 14, and Tomas, 16, will be staying as they study for their NCEA exams.
Mr Collins, a former race car engineer, had to stop working when Mrs Collins was diagnosed with breast cancer.
"Because I didn't tolerate the chemo very well," she said, "it was just too hard for him to be working when Maddie was sick and I was sick.
"So he's had to stop working to look after both of us.
"All of our savings are gone just because Maddie's disease has gone on and on and on.
"And so what money that we did have saved has now well and truly been used."
If you would like information on how to help the family, visit www. maddiecollins.co.nz