High monocyte percentage is a type of leukocyte classification count. High monocyte percentage is commonly associated with infections, in addition to blood disorders, connective tissue diseases and malignant tumors. High monocyte percentage alone cannot be clearly attributed to a specific cause and needs to be analyzed in conjunction with the patient’s condition and other examination indicators: 1. Infections: Patients with malaria, upper respiratory tract infections, infective endocarditis and other diseases may have elevated monocyte percentage, with abnormal white blood cell and lymphocyte values found in upper respiratory tract infections. If there are symptoms such as chills, high fever, and sweating, malaria cannot be ruled out and the diagnosis can be confirmed by completing pathogenic tests. If there are symptoms such as fever and bleeding spots on the skin, it may be infective endocarditis, and X-ray, CT and ultrasound examinations are needed to improve the diagnosis. For infectious diseases, the main treatment is to use sensitive antibiotics. For malaria, chloroquine and artemisinin can be used for treatment. 2. Blood diseases: monocytic leukemia, myelodysplastic syndrome, granulocyte deficiency, and other diseases can also present with high monocyte percentage. Monocytic leukemia can be determined by blood smear, myelodysplastic syndrome requires continued improvement of molecular biology, and granulocyte deficiency can be confirmed by cytology and bone marrow examination. The main treatment methods for these blood diseases are drug therapy as well as radiotherapy, surgery if necessary, and bone marrow transplantation; 3. connective tissue diseases: patients with connective tissue diseases can also have high monocyte percentage, and common diseases include gout, rheumatoid arthritis, and systemic lupus erythematosus; gout can be judged by uric acid measurement, and rheumatoid arthritis can be judged by inflammatory markers Gout can be judged by uric acid measurement, rheumatoid arthritis by inflammatory markers, and systemic lupus erythematosus by lupus band test and kidney biopsy if necessary. The disease is mainly treated with symptomatic medication and, if necessary, surgery. 4. Malignant tumors: Patients with malignant tumors such as lymphoma, lung cancer and gastric cancer may also have a high percentage of mononuclear cells, which usually requires the improvement of X-ray, CT, MRI and other examinations, as well as tissue biopsy for differential diagnosis. The main treatment methods for malignant tumors are surgery, radiotherapy, chemotherapy and targeted therapy. It is not possible to decide how to treat or what kind of disease is suffered based on a high percentage of monocytes, but the absolute value of monocytes and other laboratory test results such as neutrophils, red blood cells and white blood cells are needed to help clinical diagnosis and provide targeted treatment.