Suicide Attempt With Levothyroxine Overdose

Symptoms of levothyroxine overdose may vary depending on age, metabolism, etc. There are no specific guidelines for treating levothyroxine poisoning. Here, we present the case of a 69-year-old man with a history of panhypopituitarism, hypertension, and end-stage renal disease who attempted suicide by ingesting 60 tablets of 150 µg levothyroxine (9 mg). Upon presentation to the emergency room, he was asymptomatic despite the free thyroxine level above the range of the assay. During the hospital stay, he developed sinus tachycardia, which was controlled with propranolol. Mild elevations in liver enzymes were also noted. He received stress-dose steroids; hemodialysis was performed a day earlier, and cholestyramine was administered. Thyroid hormone levels started to improve by day seven and finally normalized in 20 days, after which the home dose of levothyroxine was resumed. The human body has several mechanisms to compensate for levothyroxine toxicity, including the conversion of excess levothyroxine to inactive reverse triiodothyronine, increased binding to thyroid-binding globulin, and hepatic metabolism. This case shows that it is possible to have no symptoms even with an overdose of up to 9 mg a day of levothyroxine. Signs and symptoms of levothyroxine toxicity may not appear for several days after ingestion, and, therefore, close observation preferably on a telemetry floor is recommended until the thyroid hormone levels start to decrease. Effective treatment options include beta-blockers preferably propranolol, early gastric lavage, cholestyramine, and glucocorticoids. While hemodialysis has a limited role, antithyroid drugs and activated charcoal are ineffective.