Thyroid nodules can be caused by many reasons.
1. Hypertrophic nodular goiter
Iodine intake is too high or too low, eating substances that cause goiter, taking drugs that cause goiter or thyroid hormone synthase deficiency, etc.
2. Tumor nodules
Benign thyroid tumor, thyroid papilloma, follicular cell carcinoma, medullary thyroid carcinoma, undifferentiated thyroid carcinoma, lymphoma and other thyroid follicular and non-follicular malignant tumors and metastatic cancers.
3. Cyst
Nodular goiter, adenomatous degeneration and cystic change of old bleeding point, cystic change of thyroid cancer, congenital thyrohyoid cyst and cyst caused by residual fourth branchial fissure.
4. Inflammatory nodules
Acute suppurative thyroiditis, subacute suppurative thyroiditis and chronic lymphocytic thyroiditis can all manifest as nodules. In rare cases, thyroid nodules are caused by tuberculosis or syphilis.