Mum of five Amanda Marshall had toddler twins, so initially dismissed her hair-thinning as a lingering post-partum problem. But, soon after, she began to get hot flushes and a racing heart. She told herself she must be going into the menopause, as she was in her early 40s. But the farmer and small-business owner from Devon was worried when she began to have what she thought were panic attacks a few months later, so in October 2016 she went to the GP. And she wasn’t expecting what they discovered.

‘I lead an active lifestyle, so I ignored my symptoms for a long time,’ she says. ‘They just crept up on me.’ Already mum to three kids with her ex-husband – Ciaran, now 24, Philippa, 22 and Roberta, 19 – Amanda had twins Ben and Toby, 12, with partner Mark, in 2013. Three years later, she started to notice her hair was breaking off.

Amanda, now 50, says: ‘I began to get hot flushes, which would come and go quite quickly, through the day. When walking up the hill from seeing to my farm animals, my heart would race and I’d start to get very out of breath, too.’

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‘I was in my 40s then, so I thought that perhaps I was in the menopause. I would come over exceptionally hot and get out of breath. Then, one day, I was standing by the stables and my heart started beating so fast that I could feel it in my chest and had to lean over. I believed I was having a panic attack and thought perhaps this isn’t what I thought it was. So that’s when I went to the doctor’s.’

Happily for Amanda, her GP acted immediately, putting her on beta-blockers for her heart, taking a blood test and spotting a lump in her neck. ‘I was with an NHS specialist in ten days,’ she says. An Ear, Nose and Throat (ENT) specialist examined the lump and identified it was her thyroid, so Amanda was referred to an endocrinologist who told her she had Graves’ disease. ‘I’d never heard of it before,’ she says.

According to the British Thyroid Foundation, around one in 20 people in the UK live with a thyroid condition. And 90 per cent of those are women. Most thyroid disorders are autoimmune conditions, where antibodies either destroy thyroid cells (hypothyroidism) or stimulate the thyroid to produce excess thyroid hormones (hyperthyroidism).

Thyroid hormones regulate the metabolism, explains Professor Kristien Boelaert, a consultant endocrinologist and president of the Society for Endocrinology and the British Thyroid Association. ‘Hyperthyroidism is too much thyroid hormone and hypothyroidism is not enough. Too much and your metabolism speeds up – you get a fast heart-rate, lose weight and get hot and sweaty,’ she says. ‘The opposite happens with hypothyroidism, so everything slows down – you gain weight, get fatigued, constipated and your skin becomes coarse and dry.’

Graves’ disease causes hyperthyroidism – although Amanda says it hadn’t caused her to lose weight. ‘Sixty to 80 per cent of hyperthyroidism in the UK is caused by Graves’ disease, which is an autoimmune condition,’ says Professor Boelaert. ‘It means you produce antibodies against your thyroid. In Graves’ disease, these antibodies stimulate the thyroid gland to make more thyroid hormones.’

The standard treatment is to start anti-thyroid medication, to block the enzyme that is responsible for thyroid hormone synthesis. Carbimazole is the most commonly used and this is what was prescribed to Amanda, in the hope it would get her thyroid back under control. It’s usually continued for around 18 months, but because Amanda’s levels would not regulate, nine months later specialists decided to operate and remove her thyroid completely. If left untreated, Graves’ disease can cause heart failure and even prove fatal.

If medication can’t make the disease go into remission, there are two other treatment options, says Professor Boelaert. 'One is to give radioactive iodine and the other is surgery to remove the thyroid gland.' She explains that surgery used to be very common 60 years ago, but is used less now, unless in very resistant cases like Amanda’s. Lower-risk treatments are favoured.

Following the surgery, Amanda now has to take thyroxine medication daily, to replace the lost thyroid hormones. Ironically, she now finds herself facing the menopause for real, as she’s in her 50s. ‘I thought: “Give me a break!” But I just have to pull up my Bridget Jones big pants and get on with it,’ she says. ‘I get the occasional hot flush and struggle to sleep, but I went on HRT and that’s helping.’

Amanda says she tries to manage day-to-day stress and does suffer from brain fog. ‘I now drop more balls than I juggle,’ she says, combining dairy farming with looking after a horse, three donkeys, two dogs and chickens, plus running her 3 Donkeys women’s overalls clothing brand.

Overactive thyroids and Graves’ disease are often mistaken for menopause, says Professor Boelaert. ‘The symptoms are often vague and commonly mistaken for the menopause. The peak time Graves’ disease occurs is in women aged around 40 and because women get sweaty, restless and don’t sleep well, they often think it’s the menopause,’ she says. ‘It is ten times more common in women than men and the GP might initially think it’s because you are going through the change.’

It’s important to get treatment, she says, as if left untreated it could result in heart-rate irregularities and heart failure. However, the good news is diagnosis just requires a simple blood test. ‘If you are worried, ask your GP for a blood test,’ says Professor Boelaert. But she cautions against using an at-home kit. ‘The over-the-counter tests are not validated; they are unreliable. Always see your GP.’

• 3donkeys.co.uk
• british-thyroid-association.org