The results of this test are used to determine whether there is hyperthyroidism or hypothyroidism, but there is no necessary link between this test and thyroid nodules. It is not necessarily related to thyroid nodules. A person with normal thyroid function can have nodules, and conversely, a person with abnormal thyroid function can have no nodules. The benignity and malignancy of thyroid nodules are mainly determined by ultrasound. Under ultrasound, the nature of the nodule, its size, whether the border is clear, whether there is calcification (fine calcification or coarse calcification), and whether the aspect ratio is greater than one, can be observed to identify benign and malignant nodules. If ultrasound cannot differentiate, fine needle aspiration can also be performed to identify them. If the nodule increases in size or has symptoms of pressure, surgery can be performed, while surgery is recommended for malignant nodules.