Elevated monocyte counts are commonly associated with infections, both viral and bacterial, with viral infections being relatively more likely to cause elevated monocyte counts. In addition, high monocyte counts can be seen in hematologic or other disorders, and in infants and children in certain physiologic conditions. 1. Viral infections. For example, infectious mononucleosis caused by EBV infection, chronic viral hepatitis caused by hepatitis virus infection, etc., the phenomenon of high percentage of monocytes will occur. 2. Bacterial infection. Such as tuberculosis caused by Mycobacterium tuberculosis infection, subacute infective endocarditis caused by streptococcus, enterococcus and other infections, etc., will also have a high percentage of monocytes. 3. Blood diseases. Acute and chronic granulomonocytic leukemia, myelodysplastic syndromes, true erythrocytosis, etc. will cause high percentage of monocytes, which may be accompanied by absolute increase of monocytes, etc., and it is necessary to do manual classification of leukocytes or bone marrow aspiration to make a clear diagnosis. 4. Other causes. Elevated monocyte percentage may also occur in cancer patients after chemotherapy. A high percentage of monocytes alone is not sufficient to determine the cause of the increase, and other laboratory tests and imaging studies are needed. If there is any discomfort or abnormality in the examination, please consult a doctor in a regular hospital in time to avoid delaying the condition.