According to one adage, general practice is like looking for a needle in a haystack. The needle is “proper pathology” – the stuff you find in medical textbooks. The haystack is the bewildering array of nebulous complaints that people bring to their doctors: pains, fatigue, palpitations, nausea, rashes, pins and needles ... The list goes on. All of these symptoms could signify something serious, yet much of the time they don’t amount to anything that could be given a diagnostic label.
I don’t agree with the adage because it implies that a general practitioner’s raison d’être is to find needles, whereas helping people make sense of their particular haystack is just as important. Nevertheless, every now and then, we will come across a needle and we must be continually alert to spot it, before it pricks our fingers.
Tim was one of my registrars – a younger doctor I was training. Cheryl was a patient he’d seen on several occasions. She had just turned 40, yet she had markedly raised blood pressure and, try as he might, Tim couldn’t get it under control. I joined him for the next consultation – he wanted advice about what to add to the cocktail of medications Cheryl was already taking – and the longer it went on, the more intrigued I became.
It was mid-October and, even though we’d had a fine English summer, most people were once again pale. Not so Cheryl. On closer inspection, there was an unusual slate-grey tinge to her tan. I scrutinised her more carefully. Her forearms, visible below rolled-up sleeves, were hirsute. Conversely, her head hair was subtly thinning in a “male pattern”, at the crown and at the temples. And although it fitted with her cheerful manner, her facial complexion was distinctly ruddy. As Tim closed the consultation, I asked Cheryl if she would mind undertaking some tests.
The pituitary gland is a pea-sized organ buried deep within the brain. It releases a variety of hormones that orchestrate our growth, metabolism and reproduction. When a benign tumour (adenoma) arises in the gland, its cells pump out far too much of their particular hormone. One of these, ACTH (adrenocorticotropic hormone), stimulates the production of steroids in the adrenal glands. An ACTH-secreting adenoma sends the adrenals into overdrive and the excess steroids eventually wreak havoc, thinning bones, provoking cataracts, elevating blood pressure, precipitating diabetes and causing heart disease – something called Cushing’s disease.
Cushing’s disease affects just ten in every million people in the UK each year, so the majority of doctors will never encounter a case in their entire working lives. The secondary conditions it presents with – blood pressure, diabetes and so on – are, on the other hand, very common. Rarely do they have an underlying cause. As a result, Cushing’s disease is extremely difficult to diagnose.
What rang a bell for me was a fact that I had learned decades before at medical school. As well as driving the adrenals, ACTH has the side-effect of stimulating pigment cells in the skin. People with Cushing’s disease have unaccountable tans. I explained my suspicions to Tim after Cheryl had left. He wasn’t convinced. Cheryl’s unusual tan could easily have been induced by a sunbed or have come from a bottle. And he hadn’t spotted the hair and facial signs that were also suggestive.
Laboratory confirmation takes weeks. Finally, the biochemistry consultant rang to say, yes, Cushing’s it was. Most doctors get a thrill when they pull off a rare diagnosis – but for the doctor who has been sifting through the hay and who failed to spot the needle, it can be painful. Things look so neat and so obvious when viewed through the retrospectoscope. Of course it was Cushing’s: that explains why her blood pressure was so difficult to treat. It was a textbook case.
An experience like that could have undermined Tim’s confidence. As well as imparting factual knowledge, one of my roles as a trainer is to prepare my registrars to cope with the ups and downs of medical life. To that end, I told Tim the story of a GP who’d been consulted by a male patient with marriage-threatening snoring – another haystack symptom. For over a year, the GP had tried in vain to help; even the ear, nose and throat specialists had eventually drawn a blank. In desperation, the patient was referred to a sleep clinic. There, a fresh pair of eyes took one look and diagnosed acromegaly, another vanishingly rare condition caused by a pituitary adenoma, this one secreting growth hormone, which enlarges the extremities, including the tongue and jaw, resulting in intractable snoring. The GP who’d failed to spot the (retrospectively) blindingly obvious diagnosis was me.
Both acromegaly and Cushing’s disease can be arrested by surgery to remove the adenoma. For doctors involved in their diagnosis, there are lessons to be learned. When we identify one, we should feel pleased but not proud. When we miss one, we should evaluate our performance honestly but we should not unduly run ourselves down.