The morning I was due to interview Adam Kay I awoke with heavy flu symptoms and a painfully frozen neck and shoulder. I was in perspiring agony and, even before I got out of bed, utterly exhausted. But I thought: what would a junior doctor do? Of course, if he or she were suffering from flu, the correct answer would be: not go anywhere near a hospital. But that’s not the sense you get from Kay’s bestselling diary of his time as a doctor training in obstetrics and gynaecology – or, as it was referred to at his medical school, brats and twats.

In This Is Going to Hurt: Secret Diaries of a Junior Doctor, hospital doctors, and in particular the author, are depicted as poorly paid, undervalued and grossly neglected professionals who are unfailingly willing to give up their own time for free to do battle with the health of the nation. That is, when they’re not trading stories about their patients’ bizarre sexual proclivities.

Doctors in Kay’s book don’t have time to be ill, because everyone else is sick and they’re busy having to deal with it. So it was in that dogged spirit that I eased myself into a vertical setting, waving away the doubts of my wife and concerned looks of strangers in the street, and gingerly made my way to meet Kay at the Wellcome Foundation in Euston, London.

Kay is now a 37-year-old comedian and scriptwriter. He’s got a round, serious face that breaks occasionally into shoulder-shaking laughter. Half-cherubic, half devilish, he looks a bit like a clean and sober John Belushi.

“How are you?” he asks politely when we meet.

This is a trick question, of course, the answer to which no doctor, or even former doctor, ever wants to hear in detail. Kay grew fed up of friends and people he met at parties recounting their ailments for his expert attention. But as he notes in his book, he prefers it to people asking him to read their scripts.

“No one’s sent me their book yet,” he says. “It’s bad enough finding time to read books I want to read, let alone those of friends of my aunt who decided they’ve an autobiography in them.”

The medical memoir is not a new idea. There have been several notable additions to the genre in recent years, including the brain surgeon Henry Marsh’s Do No Harm. But they’ve tended to focus on the ethical and the surgical, and as a consequence have conformed to a scrupulous style of writing.

That is not Kay’s approach. His is a much more personal and, not infrequently, flippant recounting of his experiences. You’re rarely a paragraph away from a punchline, and the descriptions err on the side of comic exaggeration. But it’s also full of tense situations that sometimes end in death or disability. It makes for an odd and rapid-fire oscillation between the comic and the tragic that has obviously struck a chord with the reading public.

Was he surprised by the book’s success?

“Yes,” he says immediately. “I thought that if it got an audience it would be because we all use the NHS. But the majority of people who write to me say they didn’t realise it was that bad. The NHS is such a big employer that everyone knows someone who works for it. And people are thinking, ‘I know someone who’s in that position”, rather than ‘Isn’t the human body marvellous?’”

And if Kay’s account is halfway accurate, any doctor below the level of consultant deserves the sympathy that readers appear to be giving them. The problem about assessing its accuracy is that Kay writes a lot for laughs, and his particular style of humour is to ramp up events until they seem too anecdotally perfect to be true.

But he insists the book is “reasonably accurate”, and that the main sleight of hand was to bolt the clinical data of patients to the biographical details of other patients, and change everyone’s names.