215: Choosing Wisely®: Opportunities to Reduce Intravenous Levothyroxine Use in the Icu

Introduction: Critically ill patients are often NPO (nothing by mouth) for a period of time, prompting treatment of hypothyroidism with intravenous (IV) levothyroxine (LT4). The American Thyroid Association (ATA) recommends limiting the use of this formulation to those with myxedema coma, malabsorption, or impaired enteral intake. Due to LT4’s 7-day half-life, best-practice guidelines also support delaying the initiation of IV LT4 for at least 3 days after admission or last oral (PO) dose. Guideline-discordant use increases costs and deviates from Choosing Wisely® principles. Our study sought to review IV LT4 use in the intensive care unit (ICU) and identify any opportunities for practice improvement to better align with published guidelines. Methods: We performed a single-center, retrospective chart review of ICU admissions between January 2023 and June 2025 with administration of at least one dose of IV LT4. For each admission, we reviewed indications for IV LT4 administration including NPO and clinical status. Primary outcomes included concordance with ATA guidelines, areas for cost-saving, and estimated additional costs. Results: There were 91 ICU admissions with at least one dose of IV LT4 administered, and 79 (87%) of those included at least some guideline-discordant use. Of the 436 doses of IV LT4 administered, 305 (70%) were not administered in accordance with guidelines. Guideline-discordant use was subdivided into 3 potentially co-occurring categories, 1) administration of IV LT4 within 3 days of a patient being made NPO (59 admissions or 75%) ; 2) delayed transition to oral therapy (26 admissions or 33%) ; 3) initiation based on physician preference (13 admissions or 16%). Adherence to guidelines would result in projected cost savings of approximately 18, 196–41, 477 per year. Conclusions: Guideline-discordant IV LT4 use was common among our cohort, mainly due to early initiation, delayed transition to PO formulations, and provider preference. These findings offer opportunities for improvement to support high-value care, namely through physician education and the development of pharmacy-driven guidelines to limit IV use.