Diffuse thyroid is also known as diffuse thyroid lesions. Whether it is serious or not needs to be determined by the etiology. Diffuse thyroid is described by thyroid ultrasound as a diffuse lesion; common diseases include nodular goiter, thyroiditis, hyperthyroidism, and thyroid cancer. 1. Nodular goiter: when the condition is severe, it can lead to compression of the trachea, esophagus, etc., and severe respiratory difficulties and other symptoms. 2. Thyroiditis: untreated thyroiditis may lead to hypothyroidism. 3. Hyperthyroidism: At the onset of this disease, patients may experience symptoms such as irritability and anxiety. The metabolism of the human body increases significantly, and when the condition is serious, it may lead to thyroid crisis. 4. Thyroid cancer: if it is a malignant tumor of thyroid, it may invade the surrounding trachea, nerves and so on, and in serious cases, it may have distant metastasis. Diffuse thyroid lesions should be promptly consulted and treated under the guidance of doctors.