What will happen if thyroid nodule 4a is not treated needs to be divided into circumstances, if it is benign asymptomatic thyroid nodule 4a, it may not have anything for a short time if it is not treated, but it should be followed up to see if there is any tendency of malignant change; if it is thyroid nodule 4a with compression symptoms, it may cause swallowing difficulty, etc.; if it is thyroid cancer, it may have a risk of life if it is not treated. According to the TI-RADS classification of the thyroid gland, thyroid nodule 4a belongs to the suspected malignant nodule, with the risk of malignancy ranging from 2% to 10%, and requires close follow-up or puncture to clarify the benign and malignant nature. If the thyroid nodule is large enough to cause compression symptoms, dysphagia, dyspnea and other symptoms will seriously affect the patient’s daily life; if it is thyroid cancer and not treated in time, metastasis may occur, which is life-threatening in serious cases. Patients with thyroid 4a nodules should be treated under the guidance of a doctor.