Endocrine Abstracts

Background: Hyperthyroidism is a thyroid hormone excess state which usually manifests with various cardiovascular complications such as sinus tachycardia, tachyarrhythmia and high output cardiac failure. Pulmonary embolism is not commonly associated with thyrotoxicosis but some studies have shown an increased propensity of thromboembolic disease with thyrotoxicosis. We report a case of an elderly lady presenting with hyperthyroidism, atrial fibrillation and associated pulmonary embolism.

Case: An 82-year-old lady presented to the emergency department as she felt faint, clammy and short of breath for one day. Her past medical history includes a multinodular goitre with subclinical hyperthyroidism, type 2 diabetes, pulmonary embolism post hernia repair, hysterectomy and gallstones. Bloods on admission showed predominantly T3 thyrotoxicosis, free T3 7.8 pmol/l (3.8-6.0) with suppressed TSH <0.01 mu/l (0.35-4.94) and free T4 23 pmol/l (7.5-21.1). Her anti-thyroid peroxidase antibody was positive at 108.5 kU/l (0.0-34.0) but her thyroid-stimulating antibody was negative <0.10 iu/l (<0.56). On clinical examination, her heart rate was 130 bpm and she was hypotensive but responded to fluid resuscitation. ECG showed atrial fibrillation. Her D-dimer was elevated at 4230 mg/l (<500). Pulmonary embolism was suspected given mild derangement in thyroid functions with disproportionate hemodynamic instability and CT pulmonary angiogram reported massive bilateral pulmonary embolism with saddle embolus across the bifurcation of the main pulmonary artery with pulmonary hypertension. There was some tracheal narrowing from the multinodular retrosternal goitre. The patient was initiated on standard therapy with beta-blockers, antithyroid medications, anticoagulation and planned elective radioactive iodine therapy.

Discussion: Patients with hyperthyroidism have a 10-15% chance of developing atrial fibrillation. Hyperthyroidism also predisposes patients to develop venous thrombosis or pulmonary embolism as they often have endothelial dysfunction, reduced fibrinolytic activity and hypercoagulable state which form the Virchow triad. Pulmonary embolism is a potentially fatal thrombotic disease and hence it is vital to maintain a high level of suspicion even in patients with mild thyrotoxicosis but are hemodynamically unstable.

Conclusion: Hyperthyroidism is associated with an increased risk of atrial fibrillation and pulmonary embolism. These can lead to excess mortality if it is not investigated and managed promptly.