SAT-404 Thyrotrophin Surge and Clotting Urge: Comparative Outcomes Analysis of Hyperthyroidism and Hypothyroidism with Respect to Thrombotic Risk

Abstract Disclosure: M.J. Barnett: None. J.R. Lam: None. C. Casipit: None. A. Rivadeneira: None. Introduction: Hypothyroidism is associated with decreased metabolism, affecting multiple bodily systems. Hypothyroidism appears to present a heightened risk for thrombosis through impairment of vascular flow, altered blood viscosity and disruption of fibrinolysis. The comparative risk for thrombosis in hypothyroidism over thyrotoxicosis, however, has not been explored. Objectives: The primary objectives of this study are to assess the risk for thromboses (deep venous, pulmonary emboli, central nervous system, and arterial) in patients with hypothyroidism compared to hyperthyroidism, as well as compare the survival probabilities following such events. Secondary objectives are to analyze laboratory values which may provide insight into the differing mechanisms for the heightened risk for thromboses. Methods: This study was performed using TriNetX Global Network, providing anonymized data from 145 healthcare organizations, and analyzed retrospectively. Participants were categorized into either hyperthyroidism (Cohort 1) (with > 2 instances, n = 539, 907) or hypothyroidism (Cohort 2) (with > 2 instances, n = 3,416,216). Balancing was achieved with propensity score matching, with n = 484, 944 per cohort. Participants were balanced for age (current and at index), gender, ethnicity, race, diagnosis of diabetes, hypertension, overweight/obesity, history of ischemic heart disease and neoplasia. Outcomes analyzed included pulmonary emboli, deep venous thromboses (DVT), intracranial/intraspinal thrombophlebitis, and arterial thromboses. Risk differences, risk ratios, odds ratios and Kaplan-Meier survival analyses were calculated within a 10-year observation window post-index event. Results: Following matching, thrombotic risk was lower in Cohort 1 than in Cohort 2 across multiple outcomes, including pulmonary emboli (1.4% versus 1.7%, OR 0.789, 95% CI: 0.764-0.816, p < 0.0001), lower extremity DVT (1.2% versus 1.6%, OR 0.763, 95% CI: 0.737-0.789, p < 0.0001), upper extremity DVT (0.104% versus 0.138%, OR 0.752, 95% CI: 0.67-0.845, p < 0.0001), and combined thromboses (venous or arterial) (2.8% versus 3.5%, OR 0.781, 95% CI: 0.763-0.799, p < 0.0001). There was no significant difference between intracranial and intraspinal thrombophlebitis (p = 0.078). Concerning secondary objectives, there was no significant difference in mean Fibrin D-dimer levels (p = 0.658) or von-Willebrand Factor (p = 0.962), however, mean fibrinogen levels were significantly lower in Cohort 1 (383.7 mg/dL versus 391.5 mg/dL, p < 0.0001). Conclusion: This study suggests hypothyroidism is associated with a higher risk for thrombosis, both venous and arterial, compared to hyperthyroidism, underscoring the importance of considering thrombotic complications in thyroid dysfunction. Further studies are needed to concur with these findings and provide insight into further management. Presentation: Saturday, July 12, 2025