Suzie Brown, a 42-year-old insurance claims manager, experienced relentless heart palpitations for eight months, initially attributing them to stress from her father's terminal cancer diagnosis. Her symptoms, which also included thinning hair, irritability, and unexplained weight loss, were initially dismissed or misattributed to perimenopause, despite her age.
During one episode in December 2024, her heart pounded so intensely and accompanied by chest pains that she believed she was having a heart attack. Hospital tests, including an ECG and blood work, ruled out cardiac issues, and she was discharged. Her general practitioner suggested a symptom checker, which flagged nothing significant.
By April 2025, after noticing her heart rate spiking to 180 beats per minute during a jog, as recorded by her fitness watch, Brown was advised to go to A&E. Again, initial checks were inconclusive. However, a nurse, after further questioning, suggested hyperthyroidism and arranged a blood test. Hyperthyroidism occurs when the thyroid gland produces excessive thyroxine, a hormone that regulates metabolism. This overproduction can accelerate bodily functions, leading to rapid heart rate, weight loss, anxiety, and sleep disturbances.
Professor Kristien Boelaert, an endocrinologist at the University of Birmingham, explained that the excess thyroid hormone overstimulates the heart, leading to palpitations, a faster metabolism, weight loss, tremors, and heat intolerance. She noted that symptoms can mimic those of stress or cardiac conditions, and crucially, classic menopause symptoms, leading to diagnostic delays, particularly for women.
Untreated hyperthyroidism can strain the heart, potentially causing atrial fibrillation and increasing the risk of stroke. In severe, rare cases, it can lead to a life-threatening condition known as thyroid storm.
Brown's experience is not uncommon. A 2023 survey by the University of Aberdeen revealed that individuals with thyroid disease wait an average of four and a half years for a diagnosis. Some patients with heart palpitations are misdiagnosed with conditions like panic disorder or undergo unnecessary cardiac procedures before thyroid function is tested.
Michelle Smythe, a mother of two, endured 17 months of what she described as "hell" after two unsuccessful cardiac ablation procedures for suspected supraventricular tachycardia. It was only when a third procedure was being considered that a thyroid function test was performed, revealing Graves' disease, an autoimmune condition causing an overactive thyroid. Her symptoms began during pregnancy 15 years prior, with her heart rate reaching 209 beats per minute. Despite a family history of thyroid issues, her condition was not identified sooner. Her thyroid gland was ultimately removed, and she now requires lifelong thyroid hormone replacement therapy. She was later awarded £6,000 in compensation.
After her diagnosis, Brown was prescribed carbimazole to manage her thyroid levels. While her palpitations have improved by 70%, it took another four months to find the correct dosage, and she expressed concern about the delays that put her heart under stress and increased her risk of long-term complications.
Professor Derek Connolly, a consultant cardiologist, emphasized that while palpitations can stem from various cardiac issues, thyroid disease should be a standard screening test, particularly in younger women presenting with such symptoms. A simple blood test can identify thyroid dysfunction.