What's in a gland?

For years Jane Robins felt flat and exhausted. But what she thought was her personality turned out to be her thyroid

One day last summer I drove half-way round the M25 in third gear, unable to summon the strength to change into fourth. Eventually, I arrived at my sister's house in Surrey, and asked to use the telephone. Carol suggested I use the phone upstairs in her bedroom, and I felt like crying. How come she, the mother of one-year-old twins, was leaping about like some Shirley Conran superwoman, while I, single and child-free, couldn't face climbing the stairs?

Fatigue was driving me mad. I couldn't figure out whether I was just too much of a wimp to cope with modern life, or, as the GP assured me, I had a real illness. Four years ago she had diagnosed post-viral fatigue - most likely brought on by a period of overwork plus a bout of flu and pleurisy back in 1992. Since the diagnosis I had adjusted my life accordingly, avoiding jobs that demanded irregular hours and travel, and eventually restricting myself to one demanding activity per day. I could shop only on non-working days, and manage one social event a week. Almost every evening was spent lying on the couch, exhausted.

Then, six weeks ago, my life changed. I made an appointment with a private doctor, had a detailed blood test and discovered that I have an underactive thyroid. This was incredibly exciting: my debilitating condition was immediately reversible. Every morning, as I clean my teeth, I take three tiny thyroxine pills, and I'm elated because I feel so normal. I don't dread the journey to work. I go out to dinner in the evenings. After several years of utter exhaustion, it's thrilling.

And it's frightening. I'm spending lots of money on myself - gold shoes (I couldn't have dealt with high heels before), red lipstick (on a face that launched a thousand cries of "cheer up, love"), and possibly a new car (a cherry-red convertible would be happily symbolic of this new life of mine). I'm having the 1960s psychedelic wallpaper removed from my bathroom, and am painting the kitchen. And I'm changing boyfriends: at last I have the energy. It's strange to think that what you thought was your personality turns out to be your thyroid.

I have also discovered that thousands of other people are battling on feeling exhausted and miserable - needlessly. Perhaps, like I did, they think that their unhappy state is simply the human condition and that everyone else feels the same way. It's an understandable mistake. Most underactive thyroids take years to be spotted and enormous numbers of sufferers are misdiagnosed. Every day armies of tired people complain to their doctors about feeling indefinably low, and many doctors believe that it would be too costly and a waste of money to test them all for faulty thyroids.

And yet about 1 per cent of the adult population has a thyroid problem, so it's likely that a substantial proportion of this weary army could be instantly revived. Problematic thyroids are at least five times more common in women than in men, and afflict about 3 per cent of the elderly. But they don't get much of a public profile, largely because the big drug companies are not interested in them. Correcting an underactive thyroid is amazingly cheap - the pills cost less than pounds 5 a month - and medically unexciting. Fundamentally, thyroids are boring, which is why they lack a lobby group.

The thyroid is a gland in the neck, roughly in the shape of a bow tie, which sets the metabolic rate of the body through the production of a hormone called thyroxine. If there is too little thyroxine, the rate at which each cell in the body uses energy can be affected. Muscle cells use energy to produce tension, heart cells to pump blood, brain cells to keep you conscious. If everything is out of kilter, you feel pretty bad.

The most common symptoms are a lack of energy, a dislike of cold weather and a slow pulse. It is a myth that an underactive thyroid makes you fat. You are likely to be a few pounds overweight, but nothing truly enormous. When the condition is diagnosed, the doctor doesn't have a clue about how long the thyroid has been malfunctioning, it could be months, it could be years.

It's hard to say what makes a thyroid go wrong. The most common mechanism of failure is auto-immune disease. Having lived happily with its thyroid, the body may suddenly decide that it is an alien invader and produce antibodies to attack thyroid cells. Why this happens is unclear. It may be a genetic predisposition, it may be triggered by a virus, or it may be something else.

The main thing is getting it diagnosed. If you're lucky and that happens, the sun will come out in your life. As my mother put it, it's as good as having an old aunt you never knew existed die and leave you a fortune. But beware of quack doctors inclined to prescribe thyroxine (sometimes with a diuretic) as a slimming cure. An excess of thyroxine can kill you - it can have the same effect as an overactive thyroid, which can lead to heart failure.

If you suspect your thyroid, you may have to insist on having a blood test. And if, as I did, you experience years of inaction from the NHS, it may be worth turning to a private doctor or a specialist. It could be money well spent. I know of one man who spent 10 years on a diet of boiled fish after his doctor warned of high cholesterol and heart disease, only to find out that the real culprit was his thyroid. He need never look at a boiled fish again.