MON-437 Thyrotoxicosis Factitia: A Case of Marked Troponin Elevation and Successful Management

Abstract Disclosure: E. Rosario Diaz: None. T. Patel: None. T. Hor: None. Background: Thyrotoxicosis factitia is a term to describe exogenous hуреrthуrοiԁism in the setting of surreptitious ingestion of thyroid hormone. This case demonstrates the appropriate management and important laboratory findings associated with this condition. Body: A 41-year-old male with a medical history of depression, ADHD, anxiety, substance misuse, and hypogonadism presented to the emergency department following the ingestion of an unregulated weight loss supplement containing liothyronine (LT3) 100 mcg/mL and levothyroxine (LT4) 100 mcg/mL. Prior to his presentation, the patient consumed 50 mcg of LT3 with 50 mcg of LT4 on days 1-3 and 50 mcg of LT3 with 100 mcg of LT4 on day 4, totaling 200 mcg of LT3 and 250 mcg of LT4 over the course of 4 days. He developed chest pain, palpitations, shortness of breath, tachycardia, fever, flushing, and muscle pain, which promptedhis presentation to the emergency department. The patient presented with tachycardia with heart rate 160 bpm, BP 112/89 mm Hg, fever to 101°F, with TSH < 0.008 uIU/mL (0.35 - 4.94 uIU/mL), free T3 > 20 pg/mL (1.58 - 3.91 pg/mL), total T3 5.96 ng/mL (0.35 - 1.93 ng/mL), free T4 1.4 ng/dL (0.7 - 1.5 ng/dL), and highsensitivity troponin I level (hs-cTnI) 11,304 ng/L (0 - 35 ng/L). ECG showed sinus tachycardiaand TTE revealed a left ventricular ejection fraction of 45-50%. The patient was monitored in the ICU and treated with propranolol to target a heart rate < 90 bpm, a one-time dose of dexamethasone 4 mg to inhibit T4-to-T3 conversion, and cholestyramine 4 mg TID to enhance thyroxine excretion. Markedly increased hs-cTnI was attributed to demand from thyrotoxicosis. Within 10 hours of initiating therapy, his heart rate normalized and hs-cTnI decreased to 5446 ng/L. 2 days later, TSH remained at < 0.008 uIU/mL but free T3 normalized to 3.77 pg/mL, and free T4 decreased to 0.9 ng/dL. He was discharged on day 3 in stable condition. He received extensively counselingto avoid unregulated weight loss supplements. Conclusion: This case underscores the importance of recognizing factitious thyrotoxicosis and prompt treatment to reduce thyroid hormone levels and symptoms. Rapid normalization of free T3 and reduction in free T4 can be attributed to the above treatment, but it is also important to note that thyroid hormone half-life is reduced in the setting of thyrotoxicosis. Unique to this case is the marked troponin elevation without hemodynamic or inotropic compromise. To our knowledge, this is the highest level of hs-cTnI associated with thyrotoxicosis factitia. Presentation: Monday, July 14, 2025