Background Patients often struggle to attain euthyroidism after thyroidectomy, and multiple dosing schemes have been proposed to supplant the standard weight-based approach for initial levothyroxine (LT4) dosing. The objectives of this study were to review the literature for existing LT4 dosing schemes and compare estimation accuracies with novel schemes developed with machine learning. Methods This study retrospectively analyzed 598 patients who attained euthyroidism after total or completion thyroidectomy for benign disease. A scoping review identified existing LT4 dosing schemes. 13 machine learning algorithms estimated euthyroid dose. Using 10-fold cross-validation, we compared schemes by the proportion of patients having a predicted dose within 12.5 μg/day of their euthyroid dose. Results Of 264 reviewed articles, 7 articles proposed retrospectively implementable dosing schemes. A novel Poisson regression model proved most accurate, correctly predicting 64.8% of doses. Incorporating 7 variables, Poisson regression was significantly more accurate than the best scheme in the literature (BMI/weight based) that correctly predicted 60.9% of doses (p=0.031). Standard weight-based dosing (1.6 μg/kg/day) correctly predicted 51.3% of doses, and the least effective scheme (age/sex/weight based) correctly predicted 27.4% of doses. Conclusion Using readily available variables, a novel Poisson regression dosing scheme outperforms other machine learning algorithms and all existing schemes in estimating LT4 dose.

The Chinese orbital osteology demonstrates considerable variability. The newly described anatomic variants found on the posterior ethmoidal foramen may affect surgical procedures related to the medial orbital wall. Sexual dimorphism and ethnic variations of the orbital bony anatomy may affect surgical approach to orbital diseases in different populations.

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In a significant proportion of Chinese, the supraorbital nerve exits are located toward the medial aspect of and above the superior orbital rim. Extra care should be taken during dissection around this region to avoid damage to the supraorbital nerve.