Developing a machine learning-based predictive model for Levothyroxine dosage estimation in hypothyroid patients: a retrospective study

Ngan Thi Tran ¹ Tra Huong Dang ¹ Mai Thi Quynh Ngo ¹ Dung Van Hoang ² Nguyen Van Khai ³ Linh Pham Van ⁴ Phuong Nguyen ^1*

• ¹ Faculty of Pharmacy, Hai Phong University of Medicine and Pharmacy, Haiphong, Vietnam
• ² Department of Internal Medicine, Hai Phong International Hospital, Hai Phong, Red River Delta, Vietnam
• ³ Faculty of Public Health, Hai Phong University of Medicine and Pharmacy, Hai Phong, Red River Delta, Vietnam
• ⁴ Department of Pathology and Immunology, Hai Phong University of Medicine and Pharmacy, Haiphong, Vietnam

Hypothyroidism, a common endocrine disorder, has a high incidence in women and increases with age. Levothyroxine (LT4) is the standard therapy; however, achieving clinical and biochemical euthyroidism is challenging. Therefore, developing an accurate model for predicting LT4 dosage is crucial. This retrospective study aimed to identify factors affecting the daily dose of LT4 and develop a model to estimate the dose of LT4 in hypothyroidism from a cohort of 1,864 patients through a comprehensive analysis of electronic medical records. Univariate analysis was conducted to explore the relationships between clinical and non-clinical variables, including weight, sex, age, body mass index, diastolic blood pressure, comorbidities, food effects, drug-drug interactions, liver function, serum albumin and TSH levels. Among the models tested, the Extra Trees Regressor (ETR) demonstrated the highest predictive accuracy, achieving an R² of 87.37% and the lowest mean absolute error of 9.4 mcg (95% CI: 7.7-11.2) in the test set. Other ensemble models, including Random Forest and Gradient Boosting, also showed strong performance (R² > 80%). Feature importance analysis highlighted BMI (0.516 ± 0.015) as the most influential predictor, followed by comorbidities (0.120 ± 0.010) and age (0.080 ± 0.005). The findings underscore the potential of machine learning in refining LT4 dose estimation by incorporating diverse clinical factors beyond traditional weight-based approaches. The model provides a solid foundation for personalized LT4 dosing, which can enhance treatment precision and reduce the risk of under-or over-medication. Further validation in external cohorts is essential to confirm its clinical applicability.