Dr Afsaneh Talaei, Afsaneh Talaei,
Volume 28, Issue 2 (4-2025)
Abstract
Thyroid nodules are a common clinical finding. Recent attention has been drawn to the role of insulin resistance in their development. While several studies have explored the link between metformin and insulin resistance, fewer have assessed its effects on thyroid nodules.
This study examines the impact of metformin on thyroid nodule size and thyroid hormone levels.
The present study evaluate the effects of metformin on thyroid nodule size and thyroid hormones levels.
Methods:
A total of 240 euthyroid women with thyroid nodules were divided into four groups. Group 1 received 100 mcg of levothyroxine daily, Group 2 received metformin 500 mg twice daily, Group 3 received a combination of both drugs for three months, and Group 4 served as the control group with no treatment. Thyroid ultrasound was performed at baseline and after three months. Statistical analyses included the Kruskall–Wallis, Wilcoxon, and Chi-square tests, examined the differences of the size of thyroid nodules and the mean of thyroid hormones levels between groups, for each group and to compare the percentage of differences between the groups, respectively. Also P value less than 0.05 was considered meaningful.
Results:
Kruskall–Wallis test revealed no significant differences in thyroid hormone levels between the groups after treatment, except in the levothyroxine group. Wilcoxon test showed significant reductions in TSH and increases in T4 levels within the levothyroxine group. Additionally, thyroid nodule size significantly decreased in the levothyroxine and combination therapy groups, while metformin alone had no significant effect on the size of thyroid nodules.
Conclusion:
Metformin alone does not appear to reduce thyroid nodule size. Future studies with larger sample sizes and extended durations are necessary to validate these findings and further explore metformin’s role in thyroid nodule management.
