Endocrine Abstracts

Introduction: Levothyroxin (T₄) is commonly employed to correct thyroid hormone deficiency from various causes, and as total thyroidectomy is increasingly used to treat benign thyroid conditions, lifelong treatment with optimal dose of thyroxin (T₄) is required which is difficult to predict. This study investigated factors that might predict the ideal T₄ dose, with the aim of reducing delays in achieving normal thyroid function after surgery.

Methods: This study was conducted on 48 patients presenting with benign thyroid disease that were operated upon by total thyroidectomy. The patients were prospectively randomized into two comparable groups of patients. One group of patients was given the routinely used titration method of thyroid replacement therapy, while the other used an algorithm for T₄ dosage based on patient weight which was subsequently applied in previous published literatures. Patient and operative variables that might predict time to achieve normal thyroid function and optimal T₄ replacement dose were examined.

Results: The median time to achieve normal thyroid function was 12 (range 4–24) weeks in the first group in which the traditional titration method was used where large changes in T₄ dose. But it was only 4 (range 2–8) weeks in the second group in which the weight algorithm was used. In multivariate analysis, the best predictor of optimal T₄ dose was body weight. The use of a weight-related algorithm improved time to achieve normal thyroid function.

Conclusion: The T₄ replacement dosage after total thyroidectomy is largely influenced by body weight. Use of a weight-related algorithm improves patient care compared with use of standard T₄ dose-titration methods.