Thyroid 4c is a method of grading and evaluating the benignity and malignancy of thyroid nodules using the TIRADS classification criteria. Thyroid nodule 4c is suggestive of highly suspected malignancy, with a malignancy rate of 50% to 90%, and the sequelae of doing the surgery include postoperative recurrence, decreased levels of thyroid hormones, hypocalcemia, and so on. 1. Postoperative recurrence: recurrence may occur after thyroid 4c surgery, and metastasis may also occur. After surgery, thyroid cancer patients should undergo regular review. 2. Decrease in thyroid hormone levels: T3 and T4 levels may decrease in patients after thyroid 4c surgery due to abnormal thyroid function. If the examination finds that the thyroid hormone is insufficient, it can be treated with medicines such as levothyroxine sodium as prescribed by the doctor. 3. Hypocalcemia: Thyroid 4c surgery may damage the parathyroid glands, resulting in parathyroid insufficiency and a decrease in parathyroid hormone, causing patients to develop hypocalcemia. After thyroid 4c surgery, you need to take good care of yourself, and seek medical treatment when you find symptoms of discomfort.