A "dream daughter" died after suffering sepsis which she believed was food poisoning from a steak and ale pie, an inquest heard.
Schoolgirl Tina Way, from Cardiff, blamed eating a meal at a holiday park when she became unwell and started vomiting.
Her GP believed she may be suffering from norovirus and Tina was prescribed anti-sickness and anti-reflux medication.
But the following evening the 17-year-old was found dead in bed by mum Tina Horne who desperately tried to revive her.
Ms Horne said: “I went to her bedroom and saw her lying on her back on the bed and she looked like she was sleeping.
"When I touched her she was cold and I knew she was gone."
The inquest heard Ms Horne ring for an ambulance and called Tina's father Christopher Way who had just left the house in Cardiff.
She said: "Chris, she's gone. She's gone."
The inquest heard both parents, who are separated, carried out CPR on Tina until paramedics arrived on July 20 last year.
Ms Horne said: "We have no idea what caused her death.
"We have to know what caused our dream daughter to be taken away so young."
The hearing was told Tina had been a holiday park with a friend when she ate the steak and ale pie before falling ill.
She texted her sister: "Guess who's got food poisoning?"
The inquest in Pontypridd heard Tina had been drinking lots of water in the week before her death and making frequent trips to the toilet.
In the year leading up to her death she was also suffering from anaemia and had previously been given tablets to boost her iron.
A post-mortem examination found that her kidneys were half the size of what they should be at just 60g and 55g - a normal size being 150g.
Pathologist Dr Meleri Morgan said she believed Tina had suffered multiple urinary tract infections that caused "long-standing scarring" to her kidneys.
She had developed sepsis after E. Coli, although a different strand to food poisoning, entered her bloodstream.
Dr Morgan gave a medical cause of death as E. Coli septicemia with chronic kidney disease.
GP Dr John Wakeling said he was "racking his brains" over whether there had been any clues over her kidney problems.
He said: "I had no indication that Tina had any kidney problems."
Assistant coroner Rachel Knight recorded a conclusion of natural causes.
She said: "When Tina went to her GP she did not display signs typical of sepsis."
Ms Knight added: "There was nothing obvious that could be done differently that could have changed the outcome for Tina."