SUN-374 Levothyroxine Induced Gum Bleeding

Abstract Disclosure: T. Thompson: None. F. Eshaghi: None. M. Lozano: None. K. Kumar: None. Background: Levothyroxine has been associated with various side effects, however, gum bleeding is one of the more rare side effects documented. The patient is a 52-year-old female with a past medical history significant for gastric bypass (2022) and iron deficiency who has been following with hematology for iron infusions. She reported a new onset of swollen gums with persistent bleeding. She would wake up in the morning with a pool of blood in her mouth and blood on her sheets. Her symptoms began the day after starting levothyroxine. Her coagulation labs were unremarkable, including aPTT 31 sec (24-33), fibrinogen 379 mg/dL (193-507), D-dimer 0.27 mg/L (0.00-0.49), INR 1.0 (0.9-1.1), PT 10.4 sec (9.0-11.5), Von Willebrand factor antigen 96% (50-217%), and Factor VIII 68% (50-180%), Ristocetin cofactor 78% (42-200%), Vitamin K 206 pg/mL (130-1500). Her levothyroxine was discontinued by her endocrinologist. She reports her gum bleeding stopped 11 days after stopping levothyroxine. Her endocrinologist started her on name brand of Synthroid and she had no further episodes of gum bleeding on subsequent visits. When comparing the inactive ingredients in the most common generic levothyroxine and name brand Synthroid, sodium lauryl sulfate has been associated with inflammation of oral mucosa and epithelial desquamation [1,2,3]. Butylated hydroxyanisole is another ingredient which has been associated with an increased risk of bleeding [4]. Neither of these are present in the name brand Synthroid [5]. This could explain why the patient’s bleeding didn’t return after being switched to name brand Synthroid. Conclusions: This is a case demonstrating the potential rare side effect of gum bleeding related to generic levothyroxine. References: 1.Herlofson BB, Brodin P, Aars H. Increased human gingival blood flow induced by sodium lauryl sulfate. Journal of Clinical Periodontology. 1996;23(11):1004-1007. doi:10.1111/j.1600-051x.1996.tb00528.x 2.Brito JP, Deng Y, Ross JS, et al. Association between Generic-to-Generic levothyroxine switching and thyrotropin levels among US adults. JAMA Internal Medicine. 2022;182(4):418. doi:10.1001/jamainternmed.2022.0045 3.DailyMed - levothyroxine sodium tablet. U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=e95720f2-91c9-a6d0-f7d5-8bcb94d07bbc. Published 2024. Accessed January 20, 2025. 4.Takahashi O, Sakamoto Y, Hiraga K. Lung hemorrhagic toxicity of butylated hydroxyanisole in the rat. Toxicology Letters. 1985;27(1-3):15-25. doi: 10.1016/0378-4274(85)90115-8 5. DailyMed - SYNTHROID- levothyroxine sodium tablet. www.dailymed.nlm.nih.gov. Published 2024. https://www.dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=1e11ad30-1041-4520-10b0-8f9d30d30fcc Presentation: Sunday, July 13, 2025