Podcast 860: Thyrotoxicosis

<p dir="ltr"><strong>Contributor: Travis Barlock MD</strong></p> <p dir="ltr"><strong>Educational Pearls:</strong></p> <p dir="ltr">Clinical picture: A patient comes in with altered mental status, tachycardia, fever, elevated T4, and low TSH. What’s the diagnosis?... Thyrotoxicosis secondary to Graves’ Disease.</p> <p dir="ltr">How do you treat thyrotoxicosis?</p> <ul> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">First, give a beta-blocker such as propranolol. This suppresses the elevated adrenergic activity.</p> </li> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">Second, give a thionamide such as propylthiouracil (PTU) or methimazole. This decreases the synthesis of new thyroid hormone. PTU is preferred because it also blocks the conversion of T4 to T3.</p> </li> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">Third, give an iodine solution such as potassium iodide. This blocks the release of thyroid hormone through a mechanism called the Wolff-Chaikoff effect. Note, this should be given about an hour after the PTU/methimazole to ensure iodine cannot be taken up and used to synthesize more thyroid hormone in individuals with toxic adenoma or toxic multinodular goiter.</p> </li> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">Fourth, give a glucocorticoid such as hydrocortisone. This will reduce thyroid hormone conversion from T4 to T3 and treat any concurrent adrenal insufficiency.</p> </li> </ul> <p dir="ltr"><strong>References</strong></p> <ol> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">Abuid J, Larsen PR. Triiodothyronine and thyroxine in hyperthyroidism. Comparison of the acute changes during therapy with antithyroid agents. J Clin Invest. 1974 Jul;54(1):201-8. doi: 10.1172/JCI107744. PMID: 4134836; PMCID: PMC301541.</p> </li> <li dir="ltr" aria-level="1"> <p dir="ltr" role="presentation">Cooper DS, Saxe VC, Meskell M, Maloof F, Ridgway EC. Acute effects of propylthiouracil (PTU) on thyroidal iodide organification and periph