Cytokeratin 19 fragment is the preferred marker for non-small cell lung cancer, its normal value range is less than 3.3ng/mL, if more than 3.3ng/mL, it is high, it can be seen in malignant tumors and benign diseases. 1. Malignant tumors: e.g. non-small cell lung cancer, breast cancer, bladder cancer, etc. Keratin 19 is a fragment of a cell that comes from the epithelial cells of the alveoli. When cancer occurs, a large number of cells are destroyed and a large number of cytokeratin 19 fragments are produced, giving it a high value in the blood. 2. Benign diseases: such as pneumonia and chronic renal failure. Elevated keratin 19 fragments can also indicate the presence of inflammation in the organism. It is recommended to review the test regularly and observe the changes in the indicators. If you find that keratin 19 is high, do not worry too much and do not easily make judgments. It is recommended to consult a doctor in time for a systematic examination. And find a professional doctor for comprehensive analysis and evaluation.