Positive ttf-1 refers to positive thyroid transcription factor 1, which is generally a normal physiological phenomenon, but may also be caused by papillary thyroid cancer, thyroid adenocarcinoma and other diseases. 1. Physiological phenomenon: It may be due to the normal appearance of thyroid transcription factor 1 in cells such as thyroid follicular epithelial cells and parathyroid follicular paracellular cells, and then appear positive, which is generally a normal physiological phenomenon. 2. Papillary thyroid carcinoma: usually due to papillary thyroid carcinoma, the malignant tumor invades into the surrounding cells and tissues and infects the blood, and then the thyroid transcription factor 1 is positive. 3. Thyroid adenocarcinoma: it may be due to environmental or hereditary factors, resulting in thyroid adenocarcinoma. Due to the development of malignant tumors, the blood is invaded, which in turn causes positive thyroid transcription factor 1. Thyroid transcription factor 1 positive may also suffer from cirrhotic lung cell carcinoma, eosinophilic adenocarcinoma of the lung and other diseases. If thyroid transcription factor 1 positive occurs, one should go to the hospital for examination in time, and be determined under the judgment of the doctor.