Dr Harold Bornstein said in November 2015 – a year before the presidential election – that Mr Trump had “extraordinary” physical strength and stamina, as well as astonishingly excellent blood pressure.
But in an interview with CNN, the doctor now claims the letter released during his campaign was dictated by Mr Trump himself.
“He dictated that whole letter. I didn’t write that letter,” said Dr Bornstein.
“I just made it up as I went along.”
Dr Bornstein had been Mr Trump’s physician since 1980, and the letter thrust him into public view, as the then-Republican presidential candidate was intent on proving his good health.
In September 2016, the doctor said he had written the letter, adding he had then rushed off from the appointment.
In another interview, Dr Bornstein described the moment that Mr Trump’s former bodyguard took possession of his medical records last year as a “raid”
He told NBC he felt “raped, frightened and sad” after the bodyguard and two other men showed up to take the records in February 2017.
He said the bodyguard, Keith Schiller, “created a lot of chaos” during a 30 minute visit to his office.
The White House denied anything out of the ordinary had happened.
Sarah Huckabee Sanders said: “As is standard operating procedure for a new president, the White House Medical Unit took possession of the president’s medical records.”
The White House press secretary said it was not her understanding that it had felt like a raid.
Recently Dr Bornstein told The New York Times Mr Trump takes Propecia, a drug for enlarged prostates that is often prescribed to stimulate hair growth in men.
Dr Bornstein also claims he was told he was “out” as the White House doctor after talking to the media.
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He said he was not given forms to release the medical records, and patients are usually given a copy, not the originals, which remain with the physician.
The White House has not commented on the claims the letter was dictated, or Dr Bornstein’s position in the White House.