Supplement-Induced Thyrotoxicosis Presenting as New Onset Tachycardia

ABSTRACT

INTRODUCTION: Dietary and herbal supplements can contain clinically significant amounts of exogenous thyroid stimulants and hormones, including T3 and T4, thus placing consumers at increased risk of thyrotoxicosis and other metabolic-related adverse effects. We present a case of thyrotoxicosis in a young man with no history of thyroid disease, who was found to be consuming an extensive variety of supplements. DESCRIPTION A 31 year old man with hypertension presented with 1 week of intermittent palpitations. He was in his usual state of health until 1 week prior to admission, when he noticed intermittent, self-resolving episodes of tachycardia as high as the 160s on his smart watch, associated with palpitations, dyspnea, low grade fevers, and intermittent dry cough. He came to the ED for persistence of symptoms. In the ED T 98.8 F, HR 129, BP 152/77, RR 18, SpO2 98% on RA. CBC, BMP, UA, UTox, blood alcohol content, troponin and COVID tests were unremarkable. TSH was < .007 [0.358-3.740 ulU/mL], with a free thyroxine of 0.54 [0.70-1.48 ng/dL];other thyroid studies later returned with TSI < 0.10 [0.00-0.55 IU/L], free T3 32.50 [1.80-4.60 pg/mL], and an unremarkable thyroid ultrasound. CXR showed no acute infiltrates. EKG revealed sinus tachycardia, no Wolff-Parkinson-White syndrome, and no Brugada waveforms. He was given 2L NS, ceftriaxone 1g IV, aspirin 81mg PO, and tylenol 650mg PO, and admitted to the telemetry unit. Exam revealed an anxious appearing man with tachycardia. On ROS, patient admitted to drinking 6-8 cups of coffee daily, and to taking at least a dozen different supplements. He was started on propranolol 30 mg every 6 hours with improvement in his heart rate, and was counseled to stop the supplements and wean his caffeine intake. He was discharged the following day with plan for endocrinology and primary care follow-up. DISCUSSION: Thyrotoxicosis in this young patient with no history of thyroid disease posed a diagnostic quandary. This prompted further investigation into a more detailed social history, which revealed the extensive variety of supplements he was taking, consistent with thyrotoxicosis factitia. In patients presenting with newonset tachycardia, our case highlights the importance of collecting a thorough social history and maintaining early suspicion for thyroid disease and thyrotoxicosis.