Is this why you're tired all the time? But sometimes the parathyroid gland produces too much hormone, resulting in excess calcium in the blood. Called hyperparathyroidism, this disorder can cause overwhelming tiredness. Other symptoms include abdominal pain, nausea and vomiting and, more seriously, depression, kidney stones, sudden heart attacks and osteoporosis. Scarlett had a scan that revealed the cause of her hyperparathyroidism: one of the tiny glands had become enlarged due to a small, benign tumour. This is the most common cause of overproduction of the parathyroid hormone and excess blood calcium, according to Mr Tom Kurzawinski, consultant pancreatic and endocrine surgeon at the University College London Hospitals. The condition is estimated to affect about one in 1,000 people in Britain. "The condition is four times more common in women than men, but is massively underdiagnosed in this country because GPs are not looking for it," he says. Tired All The Time syndrome is one of the most common conditions with which women present at their GP surgery. Yet very few doctors make the connection between what they may see as non-specific symptoms, such as tiredness or feeling generally unwell, and hyperparathyroidism. There is a very cheap calcium blood test which can test for hyperparathyroidism. Without it, these women will never know what is wrong. The good news is that in around 98 per cent of cases, a simple operation solves the problem. Scarlett's operation involved a small incision just above the collarbone, removal of the gland and an overnight hospital stay. A blood test for her calcium levels the following morning revealed the operation had done the trick. Once we removed the enlarged parathyroid gland, the blood levels returned to normal within five minutes. This rapid normalisation indicates a complete cure," explains Mr Kurzawinski. Scarlett calls the operation a miracle cure. "Having been on my knees with tiredness for so many years, I now have my bounce back and can function properly," she says. I would urge any woman who feels tired all the time and lacking in energy to insist on having this very simple and cheap blood test for calcium levels. Having the operation has completely changed my life.