Steroids Precipitating Acute Thyrotoxic Paralysis

Abstract

Case Description: A 34-year-old Black male was admitted with a new diagnosis of Graves’ disease and impending thyroid storm with a Burch-Wartofsky Score of 25. Initial labs showed undetectable TSH, total T3 of >800, free T4 of 7.21, and TrAb of 21.53. He was started on methimazole, propranolol, and hydrocortisone 100mg q8h. On day 2 of hospitalization, he presented with acute bilateral lower extremity paralysis shortly after eating lunch. His blood glucose was 231, and a stat BMP showed a potassium of 2.0. He was found to have thyrotoxic periodic paralysis (TPP). Steroids were stopped immediately, and he was given additional propranolol and potassium repletion. He received a total of 60mEq KCl and did not have recurrence after steroids were stopped.

Conclusion: Steroids are very commonly used in treatment of thyroid storm but can potentially exacerbate endocrine emergencies, such as thyrotoxic periodic paralysis. Additionally, demographic factors may have also decreased the likelihood of considering the potential for TPP as the patient’s race did not correspond to the most common demographics, Asian populations. Thus, it is important to be aware of the potential effects of steroids.

Clinical Significance: TPP is a rare complication of thyrotoxicosis. Excess thyroid hormones in the blood increase activity of the Na+/K+-ATPase pump, leading to intracellular shifts of potassium and consequential hypokalemia. Glucocorticoids have been shown to increase the relative amounts of Na+/K+-ATPase pumps and exacerbate hypokalemia. Steroids are one of four common treatments for thyroid storm, so their effects on transcellular ion balance must be monitored. Insulin was also found to increase Na+/K+-ATPase pump activity, explaining why episodes of TPP often correlate with carbohydrate-rich meals. Treatment of TPP, which can be done with repletion of KCl and beta blockers, must monitor for and avoid inducing a hyperkalemic state.