Last updated: 03/04/2015
Thyroxicosis is a hypermetabolic state occurring when there is an overabundance of circulating thyroid hormone (T3/T4). The condition has several common causes including Graves’ Disease, thyroid nodule, thyroiditis, amiodarone, and post-partum thyroiditis. Treatment begins with antithyroid medications followed by potentially surgical excision or radioactive iodine therapy.
- Thyrostatic medications (carbimazole, methimazole, propylthiouracil) inhibit the iodination of thyroglobulin (production of T4) by inhibition of thyroperoxidase. Additionally propylthiouracil prevents the peripheral conversion of T4 to T3. Thyrostatics take weeks to become effective.
- B-blockers provide immediate relief of symptoms until adequate treatment can be established. D-propranolol also inhibits thyroxine deiodinase blocking the conversion of T4 to T3, although this is thought to be minimal.
Surgery (total or partial thyroidectomy) is typically reserved for patients who are intolerant of antithyroid medications or radioactive iodine. Radioactive Iodine is contraindicated during pregnancy or when breastfeeding. Radioactive iodine acts by restricting or destroying overactive thyroid tissue. Radioactive iodine uptake is increased in thyroid cells especially overactive thyroid cells yielding minimal widespread side effects. Patients may have a brief period of thyroiditis for a few days following treatment and may benefit from B-blockers. Thyroid storm: Thyroid storm presents with body temperature to over 40 degrees Celsius (104 degrees Fahrenheit), tachycardia, arrhythmia, vomiting, diarrhea, dehydration, coma, and death. It is most commonly seen after illness or surgery. It requires immediate treatment with resuscitation, pharmacologic treatment with an intravenous beta-blocker such as propranolol followed by a thioamide such as methimazole, an iodinated radiocontrast agent or iodine, and an intravenous steroid such as hydrocortisone.
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