Thyroid Storm at Onset: An Uncommon Presentation of Graves' Disease

Graves' disease is an autoimmune disorder causing hyperthyroidism through antibodies that stimulate thyroxine (T4) and triiodothyronine (T3) production and release, typically presenting with a short history of hypermetabolic symptoms. Thyroid storm is a rare, life-threatening emergency resulting from thyrotoxicosis that manifests with severe multisystem involvement. Thyroid storm as the initial manifestation of Graves' disease is uncommon and can mimic other acute medical conditions, making early diagnosis challenging. We report the case of a 62-year-old woman with a background of hypertension, heart failure with preserved ejection fraction, type 2 diabetes mellitus, and chronic obstructive pulmonary disease who presented with acute confusion, dyspnoea, chest pain, abdominal pain, and vomiting. Clinical examination demonstrated hypoxia, tachycardia, and fluid overload, and as such, she was treated for acute decompensated heart failure in the High Dependency Unit setting. Despite improvement in respiratory status with intravenous diuresis, her confusion rapidly worsened, and she developed new-onset atrial fibrillation with haemodynamic instability. Further investigation revealed marked thyrotoxicosis, with a subsequent thyroid ultrasound demonstrating an enlarged and hypervascular gland. The calculated Burch-Wartofsky score was 80, highly suggestive of thyroid storm. Treatment with carbimazole, hydrocortisone, and beta-blockade led to rapid biochemical and clinical improvement, with restoration of sinus rhythm and return towards cognitive baseline. Graves' disease was diagnosed after clinical resolution with a positive thyroid-stimulating hormone (TSH)-receptor antibody titre. This case, therefore, presents thyroid storm as the first presentation of Graves' disease, masquerading as acute decompensated heart failure and delirium. It emphasises the importance of considering endocrine causes in unexplained multisystem deterioration, as early recognition and prompt treatment are essential to reduce significant morbidity and mortality.