Elevated blood mononuclear cells can be seen in physiological and pathological conditions. Mildly elevated monocytes can be observed temporarily if there are no symptoms; when the proportion of monocytes in the blood is more than 10%, it is mostly caused by pathologic factors and needs to go to the hospital for further examination and treatment. The normal range of monocytes in routine blood test is 3%~8%, and normal people can also have slightly higher phenomenon. Monocytes can be elevated in various infections, such as tuberculosis infection, viral infection, infectious mononucleosis, as well as blood diseases, lymphoma. When the proportion of monocytes in the blood is more than 10%, it should be considered that there is a possibility of the above pathologic conditions, and it is necessary to go to the hospital for further examination to clarify the diagnosis and treat the cause. However, there is a case that the proportion of lymphocytes in newborns is high, and the proportion of monocytes can be as high as 15%, which is a physiological phenomenon, and if there is no obvious clinical symptom, it can be observed first without treatment.