High cytokeratin suggests the possibility of non-small cell lung cancer or digestive tract tumor, but it does not exclude pneumonia and other benign conditions, and the diagnosis should be confirmed with the combination of symptoms, signs, chest imaging data and pathological cytology examination. Cytokeratin belongs to one of the tumor markers, the normal range is less than 3.3ng/ml, and its increase suggests that non-small cell lung cancer, such as squamous carcinoma, adenocarcinoma, and malignant tumors of bladder and gastrointestinal tract are also sometimes elevated. If the value is significantly elevated, it suggests the possibility of malignant tumors and requires CT and pathological cytology to make a clear diagnosis. With the exception of non-small cell lung cancer, inflammation of the lungs can also elevate it, but most of the elevations are small. Therefore, if cytokeratin is simply elevated in the examination without other clinical symptoms, you can follow up closely for review, if there are symptoms of inflammation, first anti-infection treatment, then review the chest CT and cytokeratin, and consider the next step of treatment according to the results of the review.