Thyroid nodule 4a, is an ultrasound grading of thyroid nodules. A thyroid nodule with a grade of 4 or higher on ultrasound is likely to be a malignant thyroid nodule, which is thyroid cancer. Therefore, a thyroid nodule with a grade 4a is likely to be thyroid cancer, and the likelihood of it being thyroid cancer is about 30%. For thyroid nodules that are considered to be thyroid cancer, surgery is usually recommended to remove part of the thyroid gland. Depending on the postoperative pathology, if it is thyroid cancer, you can take Eugenol for life after surgery to inhibit the recurrence and metastasis of the tumor. Some patients who do not want to undergo surgery and have thyroid gland 4a can have their thyroid gland ultrasound reviewed regularly, usually once in 3 months. If the level continues to rise and becomes 4b or 4c, surgery is recommended.