99-year-old Prince Philip's death certificate reportedly says he died of 'old age'

• Prince Philip died of old age, his death certificate says, according to The Telegraph.
• He received hospital treatment for a preexisting heart condition earlier this year.
• He died at the age of 99 on April 9.

The Duke of Edinburgh's cause of death has been officially cited as "old age," The Telegraph reported Tuesday.

The Queen's physician Dr. Huw Thomas said Philip died of "old age" rather than any one condition on his death certificate, which The Telegraph obtained.

The paper said this was an accepted cause of death if a person is over the age of 80 and if the doctor has personally cared for the person for a long duration and observed a gradual decline.

Prince Philip died at the age of 99 at Windsor Castle on April 9 after being hospitalized for four weeks in February and March.

He was treated for an infection and a preexisting heart condition before being discharged March 16.

He was also hospitalized in December 2019 for a preexisting condition, a palace representative said at the time, and in June 2017 for treatment for an infection.

The duke and Queen Elizabeth II received coronavirus vaccinations in January, and the royal correspondent Victoria Murphy reported in February that his hospital admittance this year was not related to COVID-19.

While "old age" can be listed as an official cause of death, the actual cause is usually an accumulation of things, as Insider previously noted.

"When most of us say that someone died of old age, what we really mean is that someone died as a result of an illness (like pneumonia) or as a result of an event (like a heart attack) that a healthy, stronger person would likely have survived," Erin Brodwin wrote for Insider.

The duke was due to celebrate his 100th birthday on June 10.

The death certificate lists his full name as "His Royal Highness The Prince Philip, Duke of Edinburgh formerly known as Prince Philippos of Greece and Denmark formerly known as Philip Mountbatten," The Telegraph reported.

The duke's first listed occupation on the death certificate is naval officer and prince of the United Kingdom. His second listed occupation is "husband of Her Majesty Queen Elizabeth II, The Sovereign," according to the newspaper.

Buckingham Palace declined to comment when contacted by Insider.