With questions being raised regarding US President Donald Trump's mental and physical health after the publication of an explosive book that claims to carry insights into his behaviour and habits, Trump is scheduled to undergo a medical examination on Friday, CNN reported on Tuesday.

“Fire and Fury: Inside the Trump White House” — an expose by author and political muckraker Michael Wolff that quotes key Trump aides expressing serious doubt about his fitness for office — hit the shelves last week despite threats of legal action.

The book's publishers had responded to a cease-and-desist letter by moving forward its release by four days. Trump had lashed out against the author, claiming that he had not authorised access to the White House for Wolff.

Read more: 6 revelations from the new book sparking 'fire and fury' from Trump

Amid other things, the book revealed that the US president prefers to eat McDonalds and has prohibited the White House staff from touching his stuff out of his fear of being poisoned. The book also raises questions about Trump's mental stability and his capability to hold the office of president.

According to CNN, Trump's medical examination later this week will be conducted by White House physician Dr Ronny Jackson. Jackson had also conducted the medical tests of former US president Barack Obama.

White House Spokesperson Sarah Sanders has promised to read out to reporters the results of Trump's exam as soon as they are available, CNN reported. However, the daily pointed out that despite Sanders' promise, the US president has the right to withhold the results from the public.

CNN added in its report that attempts had been made to contact multiple former White House physicians to learn what is routinely covered during the exams and what sort of mental health evaluations, if any, are done, but they were all unreachable or declined to comment.

The White House, however, has said that the examination will not include a psychiatric test, CNN reported.

Questions about Trump’s mental health have been part of Washington’s political gossips ever since he entered the White House in January last year but Fire and Fury pushed it on the central stage of political debates.

In the days following the release of Wolff's book, Trump had rejected the claims made by the author and defended himself against charges that he is mentally unstable.

“Actually, throughout my life, my two greatest assets have been mental stability and being, like, really smart. Crooked Hillary Clinton also played these cards very hard and, as everyone knows, went down in flames,” Trump had said in a tweet.