SAT-321 - A Thyroid Storm Is Brewing: Thyrotoxicosis in A Patient with A Cardiac Presentation

Introduction: Thyroid storm is a life-threatening condition that is characterized by severe clinical manifestations of thyrotoxicosis. It is typically diagnosed based on thyroid function tests, which will show a low or undetectable level of thyroid stimulating hormone (TSH) and an elevated free triiodothyronine (T3) or thyroxine (T4) level. In the setting of signs and symptoms of end organ damage, these abnormal lab values point towards a diagnosis of thyroid storm. Through this case, we aim to explore how thyroid storm can mask itself as a cardiac abnormality and how that creates a challenge in delineating the initial cause of a patient’s symptoms.

Methods: For this case, the patient’s chart was reviewed for vital information regarding hospital course and management. Literature review was also conducted to investigate similar cases of cardiac abnormalities observed with thyroid storm.

Case Presentation: A 71-year-old female with Graves’ disease, heart failure with preserved ejection fraction (HFpEF), and rate-controlled atrial fibrillation presented to the hospital with 3 days of persistent nausea and vomiting. Exam revealed bilateral lower extremity edema. Initial labs showed troponin of 0.53 with no EKG changes. She was admitted to the hospital for non-ST-elevation myocardial infarction (NSTEMI) and started on a heparin infusion. The next day, she was scheduled for a cardiac catheterization until she went into atrial fibrillation with rapid ventricular response. She had newly altered mental status and appeared agitated and confused. Updated labs at this time revealed an undetectable TSH and elevated free T4 to >4.0. Burch-Wartofsky Point Scale was calculated to be 75, highly suggestive of impending thyroid storm. Her catheterization was cancelled, and she was promptly transferred to the ICU and started on an esmolol infusion and IV hydrocortisone. Her home doses of methimazole and propranolol were also increased. Thyroid function tests eventually trended towards normal, and she was weaned off hydrocortisone.

Conclusion: Thyroid storm can cause cardiac abnormalities, and a STEMI/NSTEMI can cause thyroid storm; therefore, it can be difficult to delineate between an NSTEMI and thyroid storm as the inciting factor for a patient’s symptoms. Timely diagnosis is thus key, as missing a thyroid storm in a patient with an NSTEMI can cause them to undergo a catheterization involving contrast injection with a high iodine load, which can potentially worsen thyrotoxicosis. Once the diagnosis has been established, prompt treatment is crucial to prevent worsening clinical manifestations.

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