Weathering the Storm: Thyroid Storm Precipitated by Radioiodine Contrast in Metastatic Thyroid Carcinoma

Thyroid storm is an extremely rare yet life-threatening medical emergency. It results from the decompensation of undiagnosed or undertreated hyperthyroidism in the presence of an acute stressor such as trauma to the thyroid, infections, acute iodine load, withdrawal from the antithyroid medication, or surgical procedures (including thyroid surgery). Clinical features of thyroid storm include hyperthermia, tachycardia, respiratory distress, gastrointestinal and hepatic symptoms, and central nervous system dysfunction. It is primarily a clinical diagnosis, further aided by abnormal thyroid function tests. Thyroid storm is associated with significant mortality and morbidity - the latter mostly related to complications from thyrotoxicosis or hyperthyroidism. Treatment with iodine (or iodide-ionized active form of iodine) supplements or with radioactive iodine, also known as radioiodine, such as in the treatment of thyroid cancer, is a common and mostly safe practice; however, iodine contrast in tomography imaging may precipitate a thyroid storm in sporadic cases. Here, we report a remarkable case of a 62-year-old African American female with a history of total thyroidectomy secondary to follicular thyroid cancer three years before the current presentation; she developed left lung pneumonia complicated by thyroid storm status post a computed tomography angiogram of the abdomen. She exhibited signs and symptoms of thyrotoxicosis a few days after receiving the iodinated contrast. The recommended daily iodide intake for adults with hyperthyroidism is about 150 mcg per day, while a computed tomography scan exposes patients to 14 to 35 million mcg of iodinated contrast at once, which could have triggered a storm. In this case, the patient was diagnosed with thyroid storm, which was presumed to be a consequence of the Jod-Basedow phenomenon secondary to metastatic thyroid carcinoma lesions discovered later. This clinical diagnosis was reinforced by laboratory results showing elevated serum free T4 and undetectable thyroid-stimulating hormone. She was treated with supportive measures, steroids, beta-blockers, and antithyroid medications with a positive outcome. This case demonstrated that, in the setting of recurrent metastatic thyroid cancer, clinicians should approach the use of intravenous iodine medium contrast in imaging with some level of caution when dealing with patients at risk of thyrotoxicosis or with underlying hyperthyroidism state at the brink of a storm.