Leukocytosis: FOUNDATIONS OF CLINICAL SURVEY

Breviary N. Abramson, B. Melton Am Fam Physician 2000; 62:2053-60 Leukocytosis - the presence in the blood of more than 11 × / 109 / L, white blood cells - often discover during a routine laboratory examination. Increasing the number of white blood cells usually displays a normal response of the bone marrow to the infectious or inflammatory process. Sometimes leukocytosis is a manifestation of the primary disease of the bone marrow associated with the synthesis, maturation and death (apoptosis) of white blood cells, which leads to leukemia and myeloproliferative diseases. Often, family doctors can establish the etiology of leukocytosis by history and physical examination, together with the results of the expanded blood count.

Synthesis, maturation and survival of leukocytes Of the common progenitor cells - stem cells located in the bone marrow, are like erythroblasts and myeloblasts megakarioblasty. 3/4 of all bone marrow cells that contain nuclei related to the synthesis of leukocytes. As a result of the proliferation and differentiation of these stem cells produce granulocytes (neutrophils, eosinophils and basophils), monocytes and lymphocytes. Every day is synthesized approximately 1.6 billion granulocytes per kg body weight, 50-75% of which are neutrophils. More often increase in neutrophils (neutrophilia) than eosinophils and basophils. On the maturation of white blood cells in the bone marrow and their release into the circulating bed koloniostimuliruyuschie influence factors, interleukins, tumor necrosis factor, and complement components. Approximately 90% of the white blood cells are in custody in the bone marrow, 2-3% - circulate in the blood, and 7-8% are located in the tissues of the body. The cells contained in the bone marrow, are divided into two populations: those that are in the phase of DNA synthesis and maturation, and cell depot, awaiting its release into the circulation. With depot mature cells the body can respond quickly to the need for leukocytes, increasing their number doubled or tripled in just 4-5 hours. In the reaction of the bone marrow to infection or inflammation of the majority of the cells are polymorphonuclear leukocytes. Pool of circulating neutrophils is divided into two classes: those cells circulate freely, and others - are placed along the walls of blood vessels. With stimulation caused infection, inflammation, influence of drugs or metabolic toxins latter cells leave the depot and replenish freely circulating pool. As soon as the white blood cell enters the tsirkulyartornoe course and tissue survival of the cell is only a few hours. The life span of leukocytes is 11-16 days, most of which goes to mature and remain in custody in the bone marrow. The etiology of leukocytosis A survey on the leucocytosis begins with differentiation of two main reasons: 1) the proper response of normal bone marrow to external stimuli, and 2) the primary manifestations of the disease of the bone marrow. Physiological mechanisms of leukocytosis are presented in Table 1. Table 1. Pathophysiological mechanisms of leukocytosis The normal reaction of the bone marrow • Infection • Inflammation: necrosis, stroke, burns, arthritis • Stress: excessive stress, cramps, anxiety, anesthesia • The remedy: corticosteroids, lithium, β-agonists • Trauma: splenektomiya • Hemolytic anemia • leukemoid reaction Pathological reaction of the bone marrow • Acute leukemia • Chronic leukemia • Myeloproliferative disease Leukocytosis with normal bone marrow function In most cases, leukocytosis results from normal bone marrow response to infection or inflammation, the majority of cells - polymorphonuclear leukocytes (PMN). Circulating PMN and less mature forms (for example, a stick-nucleated cells and meta-myelocytes) migrate to the site of injury or infection. This process is accompanied by the release of leukocytes from the depot ("left shift"). Leukocytosis inflammatory genesis occurs when tissue necrosis, heart attack, burns and arthritis. Leukocytosis may also occur due to physical or emotional stress. This is a transient process that is not associated with the synthesis in bone marrow or release into the circulation of immature cells. Stress is leukocytosis with excessive stress, cramps, anxiety, anesthesia, and the appointment of adrenaline and disappears for several hours after the removal of a provoking factor. The remedy, splenektomiya, hemolytic anemia, and malignant diseases can also cause leukocytosis. Medications that commonly cause leukocytosis: corticosteroids, lithium and β-agonists. Splenektomiya causes transient leukocytosis, which lasts a few weeks or months. Hemolytic anemia with increased synthesis of red blood cells are non-specific increase in the synthesis and release of circulating white blood cells, it is believed that this is due to the action of growth factors. Cancers are also factors leukocytosis (and sometimes thrombocytosis) tumor nonspecifically stimulates the bone marrow to synthesize white blood cells. Overreaction to the side of leukocytes (ie, leukocytosis over 50 × / 109 / l) due to the action of factors beyond the borders of the bone marrow, called "leukemoid reaction." Usually it is caused by relatively benign processes (eg, infection or inflammation), although the most serious, though, and the rarest factor may be the malignant process. As mentioned, the increase in the number of neutrophils is the most common cause of leukocytosis, but also may increase the number and other subpopulations of leukocytes (eosinophils, basophils, lymphocytes and monocytes).