Sophie's parents went back to the clinic on Wednesday after she didn't appear to get any better and didn't have much of an appetite. They were told the original urine sample had been lost and were asked for another, but Sophie was again unable to do so at the time.
She then appeared to perk up a bit, and after two hours, they went home.
On Saturday, the Hunters were visiting family in Feilding when they woke to find Sophie yellow and listless, so they took her straight to Palmerston North Hospital.
There she was diagnosed with pneumonia and blood tests were taken, but the family were told the results wouldn't be available for 48 hours.
Sophie was wearing a breathing tube and was sitting up and talking, but started vomiting and her condition deteriorated. She was put into an ambulance and was on her way to the airfield to be flown to Auckland's Starship Hospital. Her mother was with her, with her father following.
En route, the ambulance pulled over, and Sophie died about 9.42pm.
Ms Baillie said the family was devastated and in shock.
Ms Rogerson described Sophie's parents as "awesome, caring and loving", and said "a colour had been removed from the rainbow" with the child's death.
An investigation into the death has been launched by WAM's governing body, the Whanganui Regional Primary Health Organisation.
Chief executive Judith MacDonald said she had ordered an investigation.
"Our sincere condolences go out to the parents and extended family of the little girl," Mrs MacDonald said yesterday.
The investigation was being carried out by a Whanganui District Health Board team she had asked to be involved. She said the investigation must be as "professional and objective as we can make it".
"Obviously both the police and coroner will be involved, so I'm not in a position to comment further at this stage.
"This is about gathering all the information and until that is done I won't be commenting further," she said.
Sophie's body is believed to have gone home yesterday after a post-mortem examination.