Cold nodules vs. hot nodules Thyroid nodules can be classified as “hot nodules” or “cold nodules” depending on the nodule’s ability to take up “radionuclides”. “Hot nodules are functionally autonomous thyroid nodules and are almost always benign, whereas a single “cold nodule” is generally more likely to be malignant. (Note that “multiple cold nodules” are more likely to be benign adenomas or nodules.) ”According to the data from the Institute of Oncology of Chinese Academy of Sciences, the detection rate of cancer in cold nodules is 54.5%. However, cold nodules are not always cancerous. “Cold” only means a significant decrease in iodine uptake ability. 2. Thyroid cysts, cystic nodules filled with cystic fluid and few glandular epithelial cells, will naturally appear as “cold nodules” on ECT. 3. The preparation before ECT can also affect the test results. 4. If you have eaten seafood (such as kelp, jellyfish, nori, moss strips, etc.), used iodine, or taken medications such as eugenol or thyroid tablets within two months before the test. If you have eaten sea crab and shellfish within two weeks, or sea fish, shrimp, or sea slug within one week, the absorption of isotopic iodine will be affected, resulting in “cold nodules” in ECT. In summary, although cold nodules have a certain probability of causing cancer, the clinical diagnosis should be made by combining the patient’s medical history, physical examination and other relevant tests. Therefore, there is no need to be alarmed by “cold nodules”.