Endocrine Abstracts

Introduction: Thyroid storm, a life-threatening manifestation of hyperthyroidism, presents a complex clinical challenge that demands swift and precise intervention. The heart is one of the most important target organs affected by the thyrotoxic state. Thyrotoxicosis may lead to sinus tachycardia, hypertension, tachycardiomyopathy, atrial fibrillation and heart failure.

Case Presentation: A 46-year-old female presented to the emergency department with symptoms of sweating, insomnia, diarrhea and fatigue for three months, and with increasing shortness of breath and palpitations, over the last week. She had a previous history of psoriasis and family history of her father with thyroid malignancy, who underwent thyroidectomy, at the age of 50. At observation, the cardiovascular exam revealed an irregular rhythm, with a heart rate ranging between 105 and 150 beats/min and bilateral edema of the lower limbs. She was afebrile. Thyroid function tests revealed thyroid-stimulating hormone (TSH) 0.008 uIU/ml (0.27- 4.20 uIU/ml), FT3 43.1 pmol/l (3.10-6.80 pmol/l) and FT4 >100 pmol/l (12.0-22-0 pmol/l) and TRABs 27.3 U/l (<1.58). The electrocardiogram showed atrial fibrillation. She was diagnosed with a thyroid storm, scoring 55 on the Burch-Wartofsky Point Scale. She started methimazole, hydrocortisone, beta-blocker, anticoagulant and was admitted for further stabilization and treatment. A transthoracic echocardiogram reported a reduced ejection fraction of 34%, moderate biauricular dilation, severe mitral regurgitation, and moderate tricuspid regurgitation. Over a 13-day in-hospital stay, the patient had received increasing doses of methimazole, propranolol, prednisolone, digoxin, and furosemide. However, she remained symptomatic, with frequencies between 100-120 bpm, and high levels of FT3 and FT4. On the 20th day of treatment, she developed a cholestatic pattern secondary to methimazole. The decision to perform a total thyroidectomy, with plasmapheresis before the surgery, was made. After two plasmapheresis sessions, levels of thyroid hormones decreased, and a total thyroidectomy was successfully performed. Maintaining atrial fibrillation, she underwent electric cardioversion and was discharged on the 30th day. One month later, thyroid function normalized with levothyroxine replacement. A holter revealed paroxysmal atrial fibrillation and she remained with anticoagulant and beta-blocker therapy.

Conclusion: Thyroid storm secondary to Graves disease, represents a therapeutic challenge to the clinician, especially when the hyperthyroid state leads to cardiovascular complications. Achieving a euthyroid state may resolve cardiovascular effects, but in this case, prolonged exposure to high levels of circulating thyroid hormone resulted in thyrotoxic cardiomyopathy and atrial fibrillation as sequelae.