The normal total leukocyte (white blood cells) count varies with the age of a person. It also has a diurnal cycle i.e. counts vary during a 24 hour day. Normally they range from 4000 to 10,000 per ml in an adult. Leukocytosis is an increase above the accepted normal range of total leukocytes. Usually only one type of cell is responsible for this increase, but there may be a simultaneous increase in several cell types. The counts may go up due to an increase in any component of the white cells i.e. neutrophils (called neutrophilia), lymphocytes (called lymphocytosis), monocytes (called monocytosis), eosinophils (called eosinophilia) or basophils (called basophilia). This can be judged by a differential leukocyte count. The range of each of these cells also varies with the age of an individual. There are numerous causes for increases in neutrophils, lymphocytes etc.
Monocytosis is a condition in which the absolute monocyte count is more than 1000/mcl. Your monocyte count is absolutely normal. The causes for raised monocyte count (monocytosis) are bacterial infections like tuberculosis, bacterial endocarditis, syphilis, viral infections (e.g., infectious mononucleosis), and many protozoal and rickettsial infections; malignant disorders like monocytic leukaemias, Hodgkin's disease, and myeloproliferative disorders and autoimmune disease like systemic lupus erythematosus, rheumatoid arthritis, ulcerative colitis, and inflammatory bowel disease.