Endocrine Abstracts

Introduction: Anti-thyroid drugs like Carbimazole and Propylthiouracil are widely used in the management of hyperthyroidism. These medications are associated with a spectrum of cutaneous, hematologic, teratogenic and hepatobiliary adverse effects.

Case Report: A 65-year-old lady, known to have asthma on inhalers as needed and no history of allergies. She was diagnosed with Graves’ thyrotoxicosis after she presented to her General Practitioner with mood irritability, insomnia, palpitations, and tremor of six months duration. She opted for medical therapy and was commenced on Carbimazole 30 mg per day. The patient developed lightheadedness and tongue swelling after the third dose of Carbimazole that improved with Chlorphenamine. Propylthiouracil was substituted for Carbimazole, she developed throat discomfort after the first dose and dizziness, breathing difficulty, tongue swelling and facial flushing after the second dose of the medication that required Adrenaline treatment in the Emergency Department. This case was discussed in the Endocrinology team meeting, it was felt that thyroidectomy with Potassium Iodide pre-operatively is the most appropriate treatment. She was urgently referred to our Ear, Nose and Throat surgeons and she awaits total thyroidectomy.

Conclusion: The prevalence of the antithyroid drugs-induced angioedema is unknown. While switching the patient from one anti-thyroid medication to another is the usual action in clinical practice. However, the cross-reactivity between these medications is reported to be as high as 50%. We encountered a treatment challenge in this case after the patient developed angioedema to both medications. The slow onset of disease control with radioactive iodine therapy and the risk of transient thyrotoxicosis worsening prevented us from considering this treatment option in this case.