Podcast 860: Thyrotoxicosis

Contributor: Travis Barlock MD

Educational Pearls:

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.

How do you treat thyrotoxicosis?

• First, give a beta-blocker such as propranolol. This suppresses the elevated adrenergic activity.

• 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.

• 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.

• Fourth, give a glucocorticoid such as hydrocortisone. This will reduce thyroid hormone conversion from T4 to T3 and treat any concurrent adrenal insufficiency.

References

1. 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.

2. Cooper DS, Saxe VC, Meskell M, Maloof F, Ridgway EC. Acute effects of propylthiouracil (PTU) on thyroidal iodide organification and peripheral iodothyronine deiodination: correlation with serum PTU levels measured by radioimmunoassay. J Clin Endocrinol Metab. 1982 Jan;54(1):101-7. doi: 10.1210/jcem-54-1-101. PMID: 6274892.

3. Das G, Krieger M. Treatment of thyrotoxic storm with intravenous administration of propranolol. Ann Intern Med. 1969 May;70(5):985-8. doi: 10.7326/0003-4819-70-5-985. PMID: 5769631.

4. Nayak B, Burman K. Thyrotoxicosis and thyroid storm. Endocrinol Metab Clin North Am. 2006 Dec;35(4):663-86, vii. doi: 10.1016/j.ecl.2006.09.008. PMID: 17127140.

5. Tsatsoulis A, Johnson EO, Kalogera CH, Seferiadis K, Tsolas O. The effect of thyrotoxicosis on adrenocortical reserve. Eur J Endocrinol. 2000 Mar;142(3):231-5. doi: 10.1530/eje.0.1420231. PMID: 10700716.

Summarized by Jeffrey Olson, MS2 | Edited by Jorge Chalit, OMSII