Possible causes of high carcinoembryonic antigen include tobacco, alcohol and dietary influences, female pregnancy, polyps, tuberculosis, and tumors. Carcinoembryonic antigen is a glycoprotein of human embryonic antigen characteristic, which is a tumor marker commonly used in clinic. 1. Influence of smoking, drinking and diet: High carcinoembryonic antigen may be caused by the influence of smoking and drinking before examination. High blood alcohol content, smoking stimulation, and consuming large amount of high protein food before the test will directly affect the test result. The test can be reviewed again after eliminating the interfering factors, if it returns to normal, there is no need to worry. 2. Female pregnancy: carcinoembryonic antigen test will appear high, which is normal. 3. Gastrointestinal polyps: Carcinoembryonic antigen may be high. 4. Tuberculosis: tuberculosis, bone tuberculosis, gastric tuberculosis, liver tuberculosis and other diseases may also be accompanied by high carcinoembryonic antigen. 5. Tumor: patients with digestive tract tumors, such as colorectal cancer, gastric cancer, liver cancer, and other diseases such as lung cancer, breast cancer and so on, will have high carcinoembryonic antigen. To sum up, high carcinoembryonic antigen may not necessarily be caused by tumor, but we can’t judge by this index, we need to combine the patient’s symptoms, ultrasonography, CT examination, pathology and other examination results to make a clear diagnosis, and then treat reasonably after the diagnosis is confirmed.