Non-small cell lung cancer antigen 21-1 should normally be less than 3.3 ng/ml, and 4.86 ng/ml is a mild elevation, suggesting possible benign or malignant disease. Non-small cell lung cancer antigen 21-1 refers to cytokeratin 19 fragment, also known as CYFRA21-1, which is the preferred tumor indicator for non-small cell lung cancer antigen. CYFRA21-1 is mainly found in organs rich in epithelial tissue, such as the lungs, intestines, and bladder, and elevated CYFRA21-1 is seen in benign and malignant lesions in these organs. Elevated CYFRA21-1 is mostly seen in non-small cell lung cancer, breast cancer, bladder cancer, colorectal cancer, prostate cancer, etc. The degree of CYFRA21-1 elevation is related to the tumor load.Elevated CYFRA21-1 is also seen in benign diseases such as cystitis, prostatitis, pneumonia, chronic bronchitis, etc., and it is usually mildly elevated, not more than 10ng/ml. Patients are advised to seek prompt medical attention and follow medical advice for further examination and treatment.