Dr Lisa Sanders’s absolutely favourite question is “What’s wrong with me?”. Answering it — correctly, if possible — is the sexiest part of her job. “Before I went to medical school, I thought diagnosis would be like the multiplication tables — six times eight equals a rash,” she says, laughing dryly, “but it’s not like that at all.”

Certainly not to anyone who has watched House. The television series that chronicles the diagnostic adventures of Dr Gregory House, a brilliant but crotchety doctor (played with splenetic aplomb by Hugh Laurie), is among the world’s most watched programmes. Sanders — a chatty, mumsy type from Connecticut — is its unlikely inspiration, a woman who believes proper doctors should combine the penetration of Sherlock Holmes with the bedside manner of Diana, Princess of Wales.

Sanders is as close to a real-life House as they come. She may not have a crack team and just an hour (“including commercial breaks”, as Laurie is fond of remarking) to save the day at her community hospital, but they are both genius diagnosticians — champions of the art of sizing up a patient, which makes all the difference between life and death.

Sanders, 53, has been an adviser to the show since 2004 and has just brought out a book, Diagnosis: Dispatches from the Frontlines of Medical Mysteries, about the adventures that inspire the show’s outlandish storylines. Perhaps a patient turns egg-yolk yellow and starts experiencing organ failure? Perhaps he has seizures that cause him to burst into song? Bizarrely, a lot of the cases — which, as you might imagine, can come off a tad far-fetched on screen — are based on patients that Sanders and her colleagues have seen.

She says her job is to provide these “cool stories” for the writers to work with and vet scripts for any heinous medical errors. “I have a great one that I’m going to pitch today,” she says happily. “It’s about a guy who has seizures triggered by loud noises. They’re doing a thing about a policeman so I thought it would be good.”

It’s thrilling stuff. Diagnosis opens with the story of Crystal Lessing, a young woman whose body was shutting down while her skin turned a vivid yellow. For days no doctor could work out what was wrong with her. Her blood wouldn’t clot, her organs were failing and nothing they gave her was halting the speedy passage to death.

Eventually a more senior doctor was called in. It had been assumed that the problem was her liver, but her blood contained none of the enzymes that suggested it was in trouble. Then the doctor hit on a wheeze. What if the liver was already dead when she got there? What could cause that to happen? He hit the library and came across Wilson’s disease, a rare condition that stops the body being able to process copper; eventually it explodes out of the liver and into the bloodstream.

He called in an ophthalmologist to examine her eyes. And, would you believe it, there the evidence was: two copper-coloured rings around her irises, an infallible sign of Wilson’s. Lessing was transferred by helicopter to New York for a liver transplant. Sanders’s life is packed with these tall tales: the patient with a virus that helped to kill off cancer when he infected others, or the man who went crazy in his sauna because he had drunk so much water that his body was dangerously desalinated and his brain had started to fizz.

Sanders even “solved” the mystery of the death of her own sister, an alcoholic who died in mysterious circumstances in her back garden. It was only some weeks later that Sanders figured out that because her sister didn’t eat when she was on a drinking binge, her low potassium would have tripped her heart into an instant attack.

It isn’t just the personal and dramatic that intrigues her. Even at its most basic level, she maintains, diagnostics is a tough business. In the book, Sanders quotes a study claiming that 15% of patients — in Britain as well as in the United States — are misdiagnosed on a first encounter. It’s a worrying figure, especially in a country in the grip of swine flu.

Only last week Andy Burnham, the health secretary, was grilled by an outraged Andrew Castle on the GMTV sofa when it emerged that Castle’s daughter had been prescribed Tamiflu without a proper diagnosis and — because she has asthma — suffered a respiratory collapse and almost died. Meanwhile, elders in the British medical community are constantly muttering that, because of decreasing contact time with patients and poor training, diagnostics is a lost art — especially with most of us now self-diagnosing with good old Dr Google.

“Diagnostics is the first line,” Sanders explains, “where the greatest uncertainty and mystery is. I always encourage my residents to confirm a diagnosis before they start potentially toxic therapies. Having said that, what I love about House is that when they make a mistake, they realise this is part of the process. That, as a doctor, you come up with your best guess, then your second-best, then your third-best, and you keep revisiting it until you get it right — but you’re going to make mistakes.”

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