Whether cytokeratin 4.1ng/ml is serious or not cannot be generalized, but needs to be combined with the patient’s specific symptomatic manifestations. Cytokeratin 4.1ng/ml is higher than the reference standard and can be seen in benign diseases such as pneumonia and tuberculosis, as well as malignant tumors. Cytokeratin, also known as cytokeratin 19 fragment (CYFRA21 1), has a normal range of less than 3.3 ng/ml. cytokeratin is one of the tumor markers with relatively high specificity for tumors such as cervical cancer, squamous carcinoma of the lung, and squamous carcinoma of the head and neck. Some benign diseases can cause increased serum Cyfra21-1 levels, such as tuberculosis, chronic obstructive pulmonary, acute pneumonia, chronic renal failure and cirrhosis of the liver, etc., but the concentration of Cyfra21-1 is usually not higher than 10ng/mL. If cytokeratin 4.1ng/ml is accompanied by uncomfortable symptoms, it should be examined in time to clarify whether there is organic disease, so as not to miss the condition.