The parents of a four-year-old boy with autism who died two days after being discharged from a Nottingham hospital without being given a blood test are suing over his death, lawyers said.
Harry Procko, who was born with a hole in his heart, was referred to Nottingham Children's Hospital in June after getting a severe stomach bug.
His family's lawyers say he was sent home the following day after doctors decided he didn't need blood tests. He died two days later on June 23.
A blood test taken immediately before his death found that his blood pH level was so skewed he had no chance of survival.
Harry's parents, Richard Clements and Maria Procko, from Nottingham, are demanding answers into their son's death.
Their lawyers, Irwin Mitchell, said a report ordered by hospital bosses was critical of Harry's treatment and stated there was a 'missed opportunity to perform a blood test on Friday June 20'.
They say the report also found that had there not been a failure to communicate the seriousness of Harry's condition, his death may have been prevented.
But Nottingham University Hospitals Trust said they carried out a detailed investigation into the death and "found no negligent practice by staff".
Harry's father Richard, 48, is running a campaign calling for hospital guidelines to be changed when dealing with children with special needs.
The family's solicitor Adam Wright said: "This is obviously a very difficult time for Harry's parents and they are devastated by his death.
"They just want answers as to what went wrong and why so that lessons can be learnt to improve care for others in future. We hope the NHS Trust will work with us to resolve the case quickly and fairly in light of the findings of the published report."
Dr Stephen Fowlie, medical director at Nottingham University Hospitals Trust, said: "We reiterate our condolences to the family. Our thoughts remain with them during this painful time.
"We have completed our detailed investigation of Harry's care. An external independent expert has carefully considered our investigation of this case and Report.
"Our investigation found no negligent practice by staff involved in Harry's care."
He said the report picked up "some weaknesses in our processes" which led to delays in Harry's care, but said the blood test was not thought to be necessary by treating doctors.
The hospital has discussed the findings with Harry's family and is strengthening its transfer processes, he added.