When Suzie hit her 40s, she put her thinning hair, irritability, wired brain and palpitations down to the perimenopause. Then she started to mysteriously lose weight…

For about eight months, Suzie Brown assumed the palpitations in her chest were stress-related.

‘My dad had been diagnosed with terminal cancer so I was under a lot of stress and as I was only 40 I didn’t think it could be anything serious,’ recalls insurance claims manager Suzie.

However, he was terrified by recurring, randomly pounding heartbeats and mild chest pains.

Suzie, now 42, said: ‘I could be collecting my eight-year-old daughter from school or lying in bed; ‘There didn’t seem to be any order,’ he says.

But one weekend in December 2024, four months after the symptoms first began, Suzie’s heart began beating constantly and ‘very loudly’ in her ears; Excruciating chest pains kept him awake at night.

‘I’m convinced I’m having a heart attack,’ he says.

On Tuesday, the family was so worried that Suzie’s father took her to the hospital while her husband, Ashley, 38, who also works in insurance, took their daughter to school.

Tests such as an ECG (to measure heart rate) and blood tests ruled out a heart attack and Suzie was discharged.

However, his symptoms continued.

Suzie, from Heysham, Lancashire, also started feeling hot and sweaty, so despite her young age, she wondered if it was perimenopause related.

Her doctor had her fill out an online symptom checker, but nothing checked off.

As the palpitations continued over the following months, Suzie lost a stone and a half and had difficulty sleeping.

‘Irritable and irritable’, she also noticed that her hair was thinning and her eyes felt ‘dry and gritty’.

Finally, when he went for a run one day in April 2025, he looked at his fitness watch and saw that his heart rate was 180 beats per minute (a healthy exercise rate for a 40-year-old is 90 to 153). She contacted her GP and he told her to go straight to A&E.

Once again all checks were normal, but this time Suzie stayed put. ‘I said I wasn’t happy and I knew something was wrong,’ he says. It was a nurse who, after asking a few more questions, suggested that Suzie might have an overactive thyroid gland (hyperthyroidism) and arranged for a blood test.

In hyperthyroidism, the gland produces too much of the hormone thyroxine, which controls metabolism.

High levels can cause accelerated body functions, causing rapid irregular heartbeat, rapid pulse rate, sudden weight loss despite increased appetite, as well as anxiety and difficulty sleeping, heat intolerance, and excessive sweating.

Other symptoms include itching, large amounts of urine (a higher metabolic rate causes the kidneys to filter blood more quickly), thirst, an enlargement of the thyroid gland (goiter) or thyroid eye disease (when the immune system attacks the tissue behind the eyes, creating a characteristic ‘puffy’ appearance). It may also cause erectile dysfunction in men.

It is estimated that around 800,000 to one million people in the UK have an overactive thyroid; women are twice as likely to be affected than men. The most common cause is Graves’ disease, an autoimmune condition caused by antibodies that overstimulate the thyroid gland to produce too much thyroid hormone. (It’s unclear what triggers Graves, but smoking may increase the risk.)

Kristien Boelaert, professor of endocrinology at the University of Birmingham and advisor to the British Thyroid Foundation charity, explains that excess thyroid hormone overstimulates the heart, which, along with the nerves and intestines, have a particularly high concentration of thyroid hormone receptors. This leads to a faster metabolism and potentially heart palpitations.

‘It can also cause faster intestinal transit, weight loss, shivering and heat intolerance. [feeling hot and sweaty]“as well as many other symptoms,” he told the Mail.

Symptoms of hyperthyroidism, such as palpitations, sweating, and trouble sleeping, may overlap with other common conditions such as stress and heart disease.

However, Professor Boelaert says symptoms such as palpitations, sweating and difficulty sleeping can overlap with other common conditions such as stress and heart conditions, which can make diagnosis difficult, especially for women, as they mimic classic menopause symptoms.

This can often cause delays in diagnosis; However, early detection of overactive thyroid is very important. If left untreated, constant strain on the heart can lead to atrial fibrillation (irregular heartbeat) and increased risk of stroke. In rare cases, an uncontrolled overactive thyroid can develop into a life-threatening ‘thyroid storm’; Here, the sudden and massive release of thyroid hormones into the bloodstream causes the metabolism to go into overdrive.

Symptoms include high blood pressure, fever, sweating, chills, vomiting and agitation: this is a medical emergency that can result in death in up to 30 percent of cases.

Despite the classic symptoms of an overactive thyroid, more than eight months passed before I mentioned the condition to Suzie. She had to wait another four months to see an endocrinologist, a hormone specialist.

His experience is disturbingly common. A 2023 survey of 1,200 people with thyroid disease by the University of Aberdeen found that people were waiting an average of four and a half years for a diagnosis.

Sometimes women with heart palpitations may be misdiagnosed with other conditions, including panic disorder. Others may undergo unnecessary heart examinations without being tested for thyroid function first – Professor Boelaert says that a middle-aged woman with recurrent attacks of severe heart palpitations should first have a thyroid function test.

But that wasn’t the case for 42-year-old mother-of-two Michelle Smythe, from Maidstone, Kent. He underwent two unnecessary heart surgeries because doctors mistakenly diagnosed him with a heart complaint, when in fact he had an overactive thyroid.

But after both procedures failed, a blood test was finally taken to check thyroid function, and although there was a family history of thyroid problems, the truth was revealed. Her symptoms began 15 years ago during her pregnancy, when her heart rate increased to 209 beats per minute.

Suzie’s palpitations improved by 70 percent after she started taking the drug carbimazole to control her thyroid levels.

‘I was short of breath and shaking, it was truly terrifying,’ recalls Michelle, who works as a carer and asked to use a pseudonym because of ongoing medical treatment.

He was diagnosed with supraventricular tachycardia (abnormally fast heartbeats caused by a faulty electrical signal in the heart) and was told he would need heart ablation, where heat is used to destroy the tissue that triggers the faulty signal. The five-hour procedure was performed under local anesthesia.

‘I found it extremely painful as morphine didn’t work for me,’ says Michelle.

Since the operation was unsuccessful, doctors repeated the operation three months later.

‘It didn’t work again and my palpitations continued,’ says Michelle.

It was only when her consultant was planning a third ablation that she finally ordered a thyroid function test and Michelle was diagnosed with overactive thyroid caused by Graves’ disease.

“I went through a hellish 17 months having completely unnecessary heart surgeries,” he told Good Health. ‘I don’t understand why they didn’t do a thyroid blood test when I started having palpitations.’

When he was diagnosed, his thyroid gland was so severely damaged that it had to be removed surgically.

Michelle will now use an artificial form of thyroid hormone for the rest of her life.

He was later awarded £6,000 compensation by the hospital.

‘All this trauma could have been avoided if the right test had been done at the right time,’ he says.

Suzie reflects this disappointment. After the diagnosis of overactive thyroid was made, the medication carbimazole was started to control thyroid levels; But it would take another four months for his palpitations to subside as doctors tried to find the right dose for him.

Now his palpitations have improved by 70 percent.

But he adds: ‘The delays were significant because my symptoms were gradually getting worse; ‘My heart is coming under stress, leaving me with serious long-term symptoms.’

Professor Derek Connolly, consultant cardiologist at Midland Metropolitan University Hospital, says palpitations are often caused by atrial fibrillation, high blood pressure and coronary artery disease.

However, he adds: ‘One of the things you should definitely screen for anyone who comes in with palpitations is thyroid disease with a blood test.

‘This is a standard test although it is a relatively rare cause. ‘I would look for thyroid disease in young women experiencing palpitations.’

btf-thyroid.org