Low thyroglobulin is not necessarily caused by thyroid cancer and it is not possible to determine the type of thyroid cancer solely from low thyroglobulin. Because thyroglobulin production is related to the volume of the thyroid gland, usually the more thyroid tissue is missing, the lower the thyroglobulin value will be. Thyroid cancer is categorized into papillary thyroid cancer, follicular thyroid cancer, undifferentiated thyroid cancer and medullary thyroid cancer, and all of these cancers can have low thyroglobulin after surgery. Low thyroglobulin may also be caused by congenital hypothyroidism, severe hepatitis, uncompensated cirrhosis, etc. Patients need to be actively examined. Usually, the judgment of thyroid cancer is based on the combination of physical examination, pathological cytological examination and imaging examination. If there are any uncomfortable symptoms, it is recommended to go to the hospital as soon as possible to clarify the specific condition.