Monocyte percentage of 13.9 belongs to the increased monocyte percentage, which can be categorized into physiological increase and pathological increase, and whether it is serious or not depends on the situation, and it is recommended to be judged by the physician after consultation. Clinically, the reference value of monocyte percentage is 3%-8%. Increased monocyte percentage can be seen in the following two situations: 1. Physiological increase: infants and children have slightly more monocytes in their bodies. When the percentage of monocytes is 13.9%, it is generally not serious, but it needs to be determined by the doctor according to the situation. 2. Pathological increase: Pathological increase of monocytes is mostly seen in infectious diseases (such as malaria, infective endocarditis, active tuberculosis, etc.) and hematological diseases (such as myelodysplastic syndromes, monocytic leukemia, chronic granulomonocytic leukemia, etc.), in which monocytes can be seen to be significantly increased, and its percentage can also be significantly increased. In this case, when the patient’s monocyte percentage reaches 13.9%, it is generally more serious and requires prompt medical attention. When the patient has an increased monocyte percentage, it is necessary to consult a doctor in time to identify the cause of the disease and treat the symptoms.